the artists' colour-shops in London, and has found them almost invariably to be mere rescripts of the old formula, producing their effects, such as they are, through the medium of the action of the old, or variations of the old, preparations of lead.

The varnish-maker who (when not content with wellsettled, i.e., old raw oil long exposed to air and light, nor content with refined or boiled,) would preliminarily treat his own linseed oil to get rid of the mucilage and the colouring matter, sometimes treats the oil, cold or warm, with acetate or protoxides of lead, then sometimes separates all lead by sulphuric acid; sometimes he warms the oil along with sulphate of zinc or some salt of alumina, or applies to it chlorine or some chlorine compound, &c. But the issue of the whole is, that the varnish-maker still requires something better, that is, an oil unchangeable in colour, under the high temperature, needed to dissolve the copal and other gums he has to mix with it, and that after all shall remain a fine drying oil, and as free from colour as possible; this problem, the varnish-maker has not yet solved to his entire satisfaction.

of-as it is called-" boiling" the oil, that is, by subjecting it to the action of a very high temperature, to effect its partial decomposition, or a partial or incipient destructive distillation of it, and to aid such decomposition by applying to it one or other, or all, of the materials just referred to, these being selected variously and capriciously, and, as far as the writer has ever been able to discover, without there existing among the operators the most remote notion of the real mode of action. The practice has always been, and still remains, a purely empirical one. This, then, is the practice-that of boiling linseed oil to make it dry-that has so long, and still (with but one or two exceptions, to be hereafter mentioned) universally exists in England. In most large towns or manufacturing localities, as in London, in Hull, in Liverpool, in Leeds, in Newcastle-upon-Tyne, and in Bristol, exists one or more oil-boiling establishments, where in some huge boiler, holding a few pipes or tons, is placed the oil, along with the modicum of litharge and other materials; and a strong heat from a fire, acting externally, is applied till the oil is "boiled ;" and this boiled oil constitutes the great bulk of the drying oil, whose innumerable uses and applications meet us at every step and everywhere, and for which, notwithstanding its intrinsic defects, the demand is universal and immense. The gentleman who this evening presides over this Society, eminent as well for his manufacturing and commercial enterprise as for his scientific acquirements, is himself one of the largest (if not the largest) manufac-operative painter, arises the necessity for using, along turer of this oil in the world; but even were these operations conducted everywhere with the same care, and skill, and results that are to be found and are obtained at the works of Messrs. Blundell, Spence, and Co., of Hull, there would still exist, as there now does, an urgent and universal demand, created by the vast advances in art and art manufactures in every other direction, for something better and beyond this for finer and for a greater variety of drying oils, for better rates of drying, better colour, or greater varieties of colour, and different degrees of limpidity or viscidity, to fit the various tangible but indescribable requirements of the artist and the operator, for better methods of producing them, and for the kind of labour to these ends with which this paper is concerned.

The refined oil, in paint-making, is employed chiefly as the vehicle in which to grind the white pigments. The raw oil is used to thin and prepare for use the finer kinds of paints, from which boiled oil is excluded by its dark colour and after-effects. The raw oil is of itself a very slow drier. The refined is still more imperfect in this respect-and herce, to quicken the work of the with these two, spirits of turpentine or the compositions called driers. Could the raw, or, still better, the refined, be made of themselves to dry with sufficient rapidity, or rather, could a fine drying oil, of an equally fine colour, be obtained, there would then be no need for turpentine as a drier (it would be used to produce certain art effects only) nor for driers nor for boiled oil.

It is necessary to examine in some detail the existing process of boiling, and its results. The oil to be thus boiled," as it is called, is placed in copper, or boiler plate, or sometimes in cast-iron pans, of greater or lesser capacity, according to the magnitude of the works; and this capacity may be that of one pipe of oil, or of four or six, or eight pipes. On an average, they hold four to five pipes, or about two tons of the oil. Along with the Linsced oil appears in four different forms, from one oil is mixed so many pounds of litharge, of red lead, and or other of which the manufacturer, the varnish maker, of sulphate of zinc; sometimes of acetate (sugar) of lead, and the painter, and the artist, must, each for himself, select umber, or other matters, according to the peculiar notions it, according to his special requirements. These kinds of the "boiler," so-called, par excellence, from the geneare-1st, the oil in its natural state, as it comes from the rally long experience such functionary has had in such seed, and called raw oil; 2ndly, this raw oil refined, or work, or in the establishment he is attached to. He is from which has been separated its mucilage and colour- generally some old and valued servant, pre-eminent ing matter; 3rdly, the raw oil boiled, that is, made or alike for faithfulness to the interests of his employers, intended to be made more drying than the original oil; and devotedness to the antiquated secrets of his craft. and 4thly, the raw oil put into the variety of conditions He is the very model of some old, honest, and enthuas to thickness, colour, and rate of drying that, in com- siastic alchymist, reduced to the inglorious proportions paratively small quantities, is to be found among the of a modern operative on wages, who roasts linseed oil, varnish makers, the artists' colour dealers, and others. that he may unwittingly destroy any valuable property The oils of the artist class, it may at once be re-it possesses, but which would remain unaffected, would marked, have generally more the character of curiosities than of utilities, and result from the fondling and nursing of a gallon or two of the oil over many weeks or months, sometimes exposing it to air or sunshine, sometimes eating it with acetate of lead, or with litharge, &c. Each artists' colour-maker has probably his own special mode of treatment, and not unfrequently the artist himself prepares his own oil by some favourite method. The result is generally that such specially prepared oils are by ro means remarkable for their drying properties; and the strongest the writer has met with he found to consist chemically of a solution, in any excess of oil, of the oleate of lead, and it had obviously been made by heating raw oil along with litharge and water, and afterwards expelling by heat the excess of water used. This kind dried per se in 15 hours.

The writer has carefully sought for and examined the kinds of alleged quick-drying linseed oils to be found in

he only deal with it more gently and tenderly.

To the bottom of the pan, so charged, is applied a fire, and the oil, with its contents, gradually raised to a high temperature. There is first thrown off some water, held combined probably with the mucilage in the oil, and this water forms a yellow-stained froth upon the surface of the gradually heating oil. As the heat increases, there are thrown off, successively, acetic acid, acroleine, and other vapours and gases, that give to this oil-boiling operation its distinctive but disgusting accompaniments, and make it needful that such establishments should be exiled beyond the limits of refined or civilised habitations or existences,-in London, to take refuge in Rotherhithe, on Bow-common, or in the Isle of Dogs; in Hull, in Wincolmlee or at Sculcoates; and in Liverpoal or Leeds, in some similar locality and association, where, in close juxta-position with operations on a large scale for manufacturing resin oil, for refining fish oils,

distilling coal tar, bone-boiling and grinding, and the preparation of nameless manures, it is hoped that any process of olfactory analysis of the issuing abominations may fail in detecting those that especially belong to this boiling of oil. And even in such exile, the rest they enjoy is but an uneasy one, under the eye of some sanitary official, urged into zeal by some rival interest, or by the real or imaginary spread of chemical knowledge in the community.

It is needless to say here, that on the lands of the highest class of houses, where there is at hand every needful appliance, and is ever exercised a most careful regard for public interests, these boiling arrangements are so made as to minimise and place below nuisance point the exterior evils of such a process; but wherever the oil is so treated, the occurrence to a greater or less extent of these nauseous emanations is inevitable.

Before the heat so applied to the pan has fulfilled its work upon the oil, the temperature of the oil has risen to some 600 or 700 degrees of Fahrenheit. Finally, it has suffered the changes peculiar to its incipient or partial destructive distillation, and passed from the bright yellow colour of the raw oil into a deep and permanent reddish-brown colour; and the more intense this dark colour, the better is the boiling considered to have been accomplished. Upon an average, about ten or twelve hours are occupied, from the first application of the fire, till the oil is in a condition to be still further cooled and transferred to the settling or store vats, whence, after some days, the clear oil is decanted from the sediment (called "foots"), and is in a state to be sent out as boiled oil.

And what is the cost of this operation-of the materials-the fuel and labour used-and what the ultimate value of the clear oil and of these "foots?" What the drying rate and extent of the application of this darkcoloured oil so obtained? And is there no other method of giving to linseed oil the same or more perfect drying and other properties than those realised by an operation so antiquated and impotent?

decomposed by heat, with safety. It, moreover, contains, besides the oil of the linseed, other oils, such as that of the dodder seed, and others not prevalent in the north of Europe, and which are non-drying under the old treatment; and hence has arisen a conviction in the minds of such firms as those of Messrs. Earls and Carter, of Liverpool, where the writer experimented especially upon these oils, that, on the grounds of this change in the character of the oils in the market, as well as upon other grounds, some modification or total change from the old modes, both of refining and of drying, should be sought for. The Messrs. Sissons, Bros., of Hull, not long ago informed the writer that a large batch of linseed oil, containing a large admixture of East India seed oil, which they wanted to boil in the usual manner, had so frothed up and swollen upon the application of the heat, that a large quantity overflowed through an outlet safety-pipe, and was wasted, whilst the remainder was so thick, and otherwise spoilt, as to be unfit to be applied to any ordinary purpose. As these gentlemen remarked, a repetition of such accidents as these, though in their large establishment of no moment, would be of serious importance to the smaller houses.

Involved in these topics is a question of health, now prominently before the public, viz., the lamentable discases and life-shortenings entailed upon the operatives in lead and the preparations of lead, among which preparations must necessarily be classed the kind of oil we are now speaking of. For a principal element of modern paints, viz., the carbonate of lead (white lead), there is now proposed to be substituted another substratum, viz., oxide of zinc (white zinc), and hence has arisen a contingent necessity, if we thus shall banish preparations of lead from the pigment, to banish lead also from the usual vehicle-the drying linseed oil. The vehicle so used should no, if we would follow up this movement fully, be itself, as it now is, and has always been, because of the lead in the boiled oil, the most immediate agent of those evils thus sought to be avoided. Manganesed oil, that is, the deep red coloured oil, or boiled oil, made The clear oil so obtained, even when from the very by boiling linseed oil with peroxide of mhanganese, which best makers, always contains a considerable quantity of I alluded to before, is, both because of its deep staining lead, is dark coloured-almost black, and does not, on colour, and of its imperfect drying properties, virtually exposure to air, materially bleach. It either, under the useless to this end. Oxide of zinc, per se, possesses no, most favourable conditions, develops, on drying and ex-drying properties whatever; therefore, its mixture with. posure, a dirty yellow or yellowish brown colour, or it merely raw or refined linseed oil does not result in a blackens, through reactions between the lead in it drying compound. and sulphuretted hydrogen. In paint-work, its original All kinds of existing driers" contain and depend' dark colour limits its application to coloured paints. upon lead for their drying powers. How then is From all whites, and the more delicate tints of all in- this projected substitution of zinc for lead to be terior decorations and artists' work, it either is, or should aided by any method that, without lead, shall dry the. be, absolutely excluded. Its rate of drying, per se, is, on paints so composed, or give to the vehicle the rate of an average of the best kinds, 15 hours; but, more gene-drying that is practically essential. Should it be one of. rally, when taken from the smaller makers, or from the shops, this ranges between 24 hours and 60 hours, and, too frequently, it does never properly dry.

the results of these researches, fully (as it really is,, and is submitted to this Society to be) to have solved, this problem, the writer conceives that this will not prove to this Society the least interesting part of his labours. He would, however, remark that the perfect innocuousness of oxide of zinc on animal life, has yet to be fully demonstrated; and the gradually increasing development of this branch of manufacture will speedily show this. It is however due, meantime, to say, that whilst the hideous and time-detested evils of lead are indisputable, nothing has yet transpired similarly crimi-. native of zinc.

But the process is an evidently dangerous one, as the application of a naked fire to vessels containing such inflammable matters must always be, and the fire risk in such establishments is proportional. It is an intolerable and daily increasing nuisance, both from fire risk and from smells; whilst the giving, by this treatment, increased drying powers to the oil is never certain. It ends as often, in some hands, in utterly spoiling the oil as it does in improving it. The gradually increasing importation, stimulated by the late war, into the market But a movement of this kind will not be aided by of linseed oils obtaired, not as of old, from the Baltic, overlaying its evidences. As to the evils alleged to be but from East India seed, has introduced into the old inflicted on the inhabitants of dwelling-houses that are, process a new element of uncertainty and of probable loss. or have recently been, painted with lead-compounded The difference of climate or of culture gives to the paints, worked with lead-impregnated oil (this boiled" Baltic and to the East India seed oil so different aoil), or dried by addition of lead-compounded driers, character, as to require and call for an entirely new mode of chemical treatment, not only in giving it increased drying properties, but in refining and otherwise applying it. This East India seed oil is what is called "tender." It cannot be "boiled," that is, incipiently

it is only proper to say, that they (that is, the imputed evils) are not due to the lead in this case. There is no emanation of lead from the freshly-painted walls that can be inhaled, or that otherwise can come in contact with the persons of the inhabitants. It is to the turpen

tine used to thin, and to aid in drying, and which, being to it any required degree of limpidity or viscidity highly volatile, and carrying with it (not lead, but) cer- that will fit the multifarious requirements of the matain products of the decomposition of the oil, that other-nufacturer and artist; and to accomplish this at wise would go on imperceptibly and innocuously, im- pleasure, with or without the adjunct of preparations pregnates the air of the apartments, and is inhaled, that of lead, thereby either to meet such requirements as the head-aches, the dyspepsia, and the indefinable sense the old habit and style of oils may still perpetuate, of disorder, discomfort, and depression, in a newly- or to meet the growing convictions that a more harmpainted house, are chiefly due. Here, to the inhabitants less class of paints and paint materials should be merely, there is brought about no actual contact with adopted. the lead. Those who actually handle the paint are the persons who suffer the operative painter, and the operative manufacturer of the lead pigments, of the leadcompounded driers, and of the boiled oil.

II.-Review of Known Resources for Solution.

For the pure chemistry of the oils and of fatty matters it is needless here to say, that the chemical The scientific vigilance of the French Government world was, and is still, indebted chiefly to the researches takes care to propagate everywhere such knowledge, of Chevreul, undertaken and completed some forty bearing upon the physical welfare of its people, as che-years ago; and that it is singular how completely mistry or physiology may bring to its notice; and, these researches and their results have both fixed the among the rest, they encourage in every way the character of this branch of chemistry, and either prespreading abroad among the operatives a knowledge of cluded or obviated subsequent inquiry. But the labours the sad evils entailed upon them by handling and of Chevreul went to determine their chemical constiworking with pigments, paints, and other preparations tution, not to investigate their peculiar changes under containing lead. And the writer has just been told, by all kinds of extraneous action; and the peculiar cheone well conversant with Parisian proceedings of this mical history of the changes the drying oils undergo kind, that the Government will now admit of no con- under the various conditions here concerned, formed tract for public works for paints that contain lead. no part of his admirable researches. Both the manuThat, although prohibitively to restrict the use of facturing and the chemical world have, in this case, these is beyond the sphere of an Imperial decree, by pro- seemed content to accept as a sufficient explanation ceedings so significant as this of their contracts, they that of the oxygen absorption, without thinking that instruct and intimate the importance they attach to the this fact might be only one of many actions simultasubject. neously at work, or of a series of complicated changes, each of importance, and requiring to be studied before the subject could be understood, and this understanding be brought to bear upon any processes for improving industrially this branch of manufacture. The more modern organic chemistry, with its accurate manipulations, and the blaze of light it has and will yet throw upon this and kindred subjects of inquiry, has hitherto in its brief career had too many other objects to be devoted to, or so few real workers to undertake them, as to have passed over almost entirely this mere section of so large a field. The result has been that this question of the phenomena involved in the drying of oils had not yet passed through the ordeal of the minute and complete examination moderu organic chemistry was capable of effecting, and consequently there had been made no inroad upon either the old theories, or upon the facilities of testing the oils in order to improve their drying properties, that the daily and vast importance of the subject would seem to have merited.

The oil-boiling trade in England is divided chiefly between two classes:-the paint manufactures and grinders, who boil oil for their own use and for their own sale, and the oil boilers and refiners, who receive from the oil merchants and from consumers-not themselves boilers the raw oil, put it through the operation, and return it at a certain charge per ton. Those of the former class, generally, in every respect, persons of high character and position, have obviously every motive of interest, had they none other, to do their work well; but those of the latter class (with many most honourable exceptions) have so conducted the business as to reduce it to a most disreputable position. By some of these the oil sent them is sometimes never boiled at all. It is coloured in some way, and returned at a charge of from 30s. to 40s. per ton. In other cases, a hundred weight or two of the genuine raw oil is abstracted, and its place supplied with an equal weight of common resin. In others, the abominable addition is made to it of a quantity of resin oil. If it be known to be for export, and the chances are The existing practice, that has been described above, is against any examination before departure, any descrip- itself of course older than the comparatively more recent tion of refuse stuff, in no other way saleable or usable, will alleged explanation of its chemistry. It is older than the be mixed with the genuine oil; and in due time, some time of Scheele and the epoch of the chemical philosophy victim, in one of our remote colonies, finds the paint it has of Lavoisier; for oxygen and its reactions, real or supcost him so much money and care to provide never dries; posed, in the case, were not known or recognized for so very pleasingly, of course, convincing him of the im-long a time as litharge and its reactions upon oil have proving moralities of the mother country. The practical evils of such a system are met with daily and everywhere.

To relieve a wealthy and most important class of persons from this abominable system, by providing them (each for himself, if he wish) with the means of treating their own oil on their own premises, saving both carriage, boiling charge, and the chance of deception, and producing oil of any colour and quality that may be required, is another of the practical results of the researches this paper is intended to submit to the Society. This, then, is the problem-to take the raw oil, and by some process, free from danger, fulfilling its objects at an ordinary temperature, or, at most, under a steam heat, free from noxious or unpleasant accompaniments, simple, cheap, and expeditious-to give to the raw oil an efficient rate of drying property that can be modified at pleasure; to give to it any colour, ranging between the dark brown of the old boiled and the straw colour of the refined, or a better, if that be possible; to give

been. But both the practice and its chemical explanaation are sufficiently antiquated to have led to the hope that the application to the phenomena of this branch of industrial chemistry, of the laws and appliances of modern organic chemistry, would surely result (as in so many other instances) in throwing some light upon, or in giving a truer and more satisfactory interpretation of, the chemistry involved in them.

But mere analysis did not furnish the information sought for. The expression, in correct formulæ of the composition of the linseed oil, in its original normal condition, as obtained from the seed, and a similarly accurate expression of its composition, when it had became solidified, threw no light whatever upon changes whose intermediate character, or the character of the series of results intermediate between the normal and final condition of the oil, were probably as important to the end in view as the original and the final conditions themselves were.

Analysis, therefore, would not, and did not, supply

or disturbed; and to watch under the microscope, and
determine the amount of this action or influence, and
the kinds of mixtures that best produce it, constitutes
by no means the least interesting of the curious pheno-
mena developed in the course of these experiments.
IV.-Results and Dedictions.

of cobalt, of nickel, of manganese, of tungsten, and numerous others. There were also applied alumina, lime, soda, potash, magnesia, sulphur, ammonia, and their salts of every variety, and varied in every way by using them (both these and the former) in their dry (i. . anhydrous state) and with their constitutional water and their water of crystallization in every instance on which they assumed or were capable of being placed Confining a brief summary of results to the main obin these different chemical conditions. In like manner,ject in view, those sugsestive of the manufacturing opemoreover, was the oil submitted to the action of iodine, of rations to be adopted, and omitting a variety of instrucbromine, of chlorine, of cyanogen, of sulphurous acid gas, tive and curious phenomena thrown out in the course of and the gaseous oxides of nitrogen, and others, and also, of so much experimenting-such, for example, as the pecourse, to the more readily obtained action of the hydrated culiar texture of paints, or surface appearances when dry, acids, the acetic, the sulphuric, the oxalic, the hydro-produced by unusual mixtures of materials; the various chloric, and the nitric. degrees of "gloss," and of "flat," unexpectedly deveExperiments so ordered were multiplied into hundred:;loped, and suggestive of new modes of producing these and the first conspicuous results were to reduce to only effects; the curious phenomena of molecular disturba mere few the materials that out of all these had any ances, already alluded to, when watched under the mispecific action at all of the kind here sought for or desired, croscope, and yielding curious art effects, that an artist, viz., a drying action, unaccompanied by any other action provided with sufficient chemistry and his microscope, that precluded the application of the agent so effecting and who would penetrate into some of the inmost reit to the purpose in view. The result is indeed finally cesses of the chemico-mechanism of his craft, might con(as will be seen afterwards) to reduce this number practi-vert into a study of infinite interest and utility; omitting cally to two or three, because these peculiar actions, fitted indications of the pure chemistry of the successive exactly, and better than any others previously em- changes in the oil, yet to be thoroughly determined, and ployed, all the requirements in drying oil in its various expressed in accurate formula-omitting these, and many applications; and the next conspicuous result was to show others, the summary of practical results may be given that such of the above substances as did exercise this briefly as follows:specific action, were equally effective when either the smaller or the larger proportion was used, that is, the oil dried as well under the action of the 5 parts to the 100, as under the 10, the 15, or the 20 parts, and that, therefore, this action was not of a kind belonging to that class of chemical actions depending upon reactions between elements in equivalent quantities, but of some other and yet undetermined kind.

When an oil, or an oil paint, on exposure to air, dries, four distinct kinds of action come into play, to effect, or to contribute to, that result. These are

Firstly. The chemical actions taking place naturally (and unaided by any other contingent action) between the oil and the atmosphere, and atmospheric influences, or the natural chemical action consequent on exposure.

Secondly. Those due to some specific chemical action upon the oil of some element in the pigment, or of some element added to it specially to initiate or aid the action that follows upon exposure, or the induced chemical action, as contra-distinguished from the natural.

Thirdly. Those due to the peculiar physical structure of the composition of the paint, through which, within the same superficial area, a larger surface of the oil is brought under the action of atmospheric agencies.

This series of experiments was followed by another, in which, instead of using the several chemical substances alone, a variety of compounds, mutually reacting with each other, were mixed together along with the oil, and their mutual or contingent reactions upon the oil clearly noted; and it was out of this latter series that there came finally the processes which it is more especially the object of this paper to submit to your attention, and that, in the judgment of the writer, are destined to act in future so important a part, both in improving the processes to be applied, to the treatment of these oils, and because of the extraordinary results in the qualities and varieties of the oils so obtained, in thus extending the sphere of the ap-up to the action of the atmosphere, by which the atplication of drying oils.

Another long series of experiments, (still conducted on the same general principle of searching, by multiplied trials, and out of the consequent multifarious results, for new or crucial phenomena), had for its object to discover how results obtained under the former series, when the materials whose specific action upon the oil was investigated, per se, were modified, when, in addition to the drying compound, or the compound whose drying or contrary action was to be determined, there was mixed with the oil some material intended to bring the mixture into the condition of an ordinary paint, so far as regarded the relative proportion of the oil and of the pigment; and the pigments chosen for this purpose, to mix with the oil, or along with any other experimental material added to it, were as already mentioned, the oxide of zinc and lamp-black, used, of course, separately and comparatively.

To this series was added another, intended to determine the character and amount of action of another kind that the former series had given traces of, viz., the purely mechanical action (not chemical) caused by materials mixed with the oil, mutually reacting among themselves, and, in 'so reacting, giving birth to a molecular action or disturbance of the oil, and thus causing it continually, during such action, to present fresh surfaces of the oil to the action of the air. An oil so mixed and subjected dries much sooner than one not so agitated

Fourthly.-Purely mechanical actions, brought about by molecular disturbances in the oil or paint, by which fresh particles of the oil or fresh surfaces of it are being, during the time of exposure, continually thrown

mosphere is admitted interstitially as well as superficially to act upon the oil. These molecular disturbances are caused by the admixture with the paint of some volatile fluid, as turpentine, and its evaporation;by the escape of water of crystallization of some salt or other added to it; or by chemical re-action and combinations taking place between the elements of the pigment, or between it and some other, or between some other elements added, and resulting in the formation of some new compound, or in some act of crystallisation or other changes of form; and often in the liberation of previously combined water, &c., &c. The materials whose re-actions yield those purely mechanical actions are, of course, such as do not, of themselves, act chemically upon the oil, but act simply by creating in it a movement of its particles during the time of exposure of the paint for the purpose of drying it.

In any instance of an oil or a paint drying, the influences at play to contribute to that result can be traced to one or other, but most frequently to the combined effect of two, or of all of those kinds of actions.

If a given weight of any drying oil be spread in a thin film over a given area-say 100 square inches-it may dry in (say) 20 hours, under the natural chemical action of atmospheric exposure and influences.

If oil of the same kind and weight be ground up to the consistency of an ordinary paint, with some material