intense that a few drops of this water were sufficient to communicate to a cupful of milk or any inodorous liquid, the agreeable aroma of coffee.

The particles of concrete essence were not the source of this aroma; for, isolated and washed, they did not appear to retain any thus, the aromatic matter was entirely soluble in water.

The third receiver, cooled several degrees below the freezing point, condensed a few drops of water exhaling the mixed odor of coffee and of the pyrogenous hydrocarbons; the latter odor existed especially in the fourth receiver, equally cooled, but whose sides had condensed only traces of moisture; the same empyreumatic odor predominated even in the aeriform matters which issued from the fourth receiver. The presence of carburetted hydrogen in the gases was proved by passing them into a tube with bulbs full of concentrated sulphuric acid: this acid acquired a deep brown color, and a deposition of carbonaceous matters took place when the acid was diluted with water.

The presence and proportions of the carbon in these gases may be determined by directing them through a tube for elementary analysis filled with binoxide of copper, and collecting the carbonic acid disengaged.

The proportions of the very volatile empyreumatic carburets with a disagreeable odor increased more and more when the roasting of the coffee had been carried from that which corresponds to a loss in weight of 0.18 to that which is equivalent to the loss of 0.25 beyond.

It is evident that it is possible to isolate the residue and the products of an infusion of coffee, so as to retain, in a form reduced to a bulk of, the greater part of the aromatic principles. These latter are complex; two odoriferous essential oils may be extracted from them. It is sufficient, for that purpose, to strongly agitate the distilled water which contains them, with 0-20 of its bulk of ether; it is left to repose for a quarter of an hour, when the supernatant ethereal solution is removed with a pipette. This operation is repeated four times, and the evaporation of the ether leaves an orangecolored oil, the very powerful odor of which partly resembles the aroma which prevails more or less in all varieties of coffee. Ten grammes of the water distilled from Mocha coffee gave one centigramme of this oil, taking account of the waste during the evaporation of the ether, which waste may be determined by dissolving this essence a second time in ether, and weighing again after a second evaporation. This essential oil was formed of two parts; one, less volatile and less fluid,

appeared to result from the alteration of the oil possessing the most agreeable aromatic odor. There remained in the water, agitated with ether, an etherial solution of the second essence, endowed with a very sweet aromatic odor; its proportions, small in the inferior qualities, but large in Mocha coffee, appear to constitute the principal differences between the commercial qualities. It may easily be extracted by placing pieces of chloride of calcium in the first two receivers ; the solution of the chloride raises the temperature in these vessels as the vapor condenses in them. A third receiver, surmounted by a tube filled with chloride of calcium, cooled to 68° F., retains, with the saline solution, almost all the aromatic essence which is extracted by means of ether. The total weight of the essence thus obtained amounted at most to two ten-thousandths of the weight of the coffee, and this may be understood, since one drop of this oil diffused over a room a strong odor of coffee.

The variable qualities for a long time observed in the coffees of commerce are owing chiefly, doubtless, to the varieties cultivated, and to the habitual or accidental circumstances of vegetation, such as exposure, soil, locality, the care taken in cultivation, and the atmospheric conditions. It would be interesting to endeavor to determine the influences of these different causes on the qualities of the product.

I devoted attention to discovering the principal differences between two commercial varieties, concerning the origin of which I could not have the least doubt-Martinico and Mocha coffees.

The first is ordinarily in large berries, presenting a depressed face; some berries, rolled in ellipsoïds, proceeding from fruits of which one of the ovules was absent. Some berries, still more rare, have a slightly angular form, dependent on the presence and the mutual pressure of three ovules in the same fruit.

Mocha coffee differs from the foregoing in that its berries have a yellowish grey color; they are smaller, their forms more irregular, very generally flattened on the side, which is in contact with another berry in each of the fruits. Some berries only are rounded, because they are found, each separately developed, in a fruit in which one of the ovules is wanting.

Many characters distinguish Mocha coffee from all others; the fatty matter, which is rather more abundant, forms 13-hundredths of the total weight; I could separate only two parts having different points of fusion, difficult to determine. It retained more powerfully a portion of the aromatic essence, sweeter, and in greater quantity.

The fatty matter of Martinico coffee, extracted by the same means and exhausted by boiling water, is browner and less fluid; it may be separated into 4 parts, whose melting points are, respectively, 41, 65, 122, and 194° F. This last part resembles the wax of leaves.

The presence of a waxy matter and the green color of the berries might depend on the period of gathering and the time at which the barking was performed. In removing the pulp of the fruit when it is full of juice, the perisperm being quite moist, must undergo in the air certain re-actions to which oxygen gives rise: thus the chloroginate undergoes partially the green transformation, the fatty substances are altered, and the essence, less abundantly secreted, may thus be altered and partly escape.

These hypotheses, which agree with the results of analysis, led to the idea that the quality of certain coffees might be improved by allowing them to come to a more complete degree of maturity before the decortication. Perhaps if a portion of the crop was left to ripen and dry, a quality would be obtained analogous to those mixtures of Mocha coffee with green coffees-of which many people prefer the mixed aroma to the more soft aroma of the pure Mocha. This interesting subject, with observations made in our colonies, might be concluded, in France, with analytical experiments.

The influence of the period of gathering, and of a particular mode of decortication, seems to me to be manifested also in the results of the preparation of a very peculiar kind of coffee, called Yungas in Bolivia. This sort is in regular bulky berries of a yellowish grey color. Under these appearances, we see only a light envelope in which lies a perisperm of the same form and similarly marked; but which, having shrunk more considerably by desiccation, is much smaller than the berries of ordinary coffees. In order to obtain this kind of coffee, it is gathered and barked very long before maturity. It is a fancy coffee which the Bolivians prefer, doubtless from custom, although it developes less of the soft aroma which characterises Mocha and several varieties generally esteemed.

In combining the different analytical results, it was found that coffee in the normal state, presents as nearly as possible the following composition:

It would be very interesting to know the special effects, in the animal economy of the well-characterised substances which enter into the composition of coffee, and are not found in any of the matters proposed as a substitute for it-what is the action of caffeïne which is so little alterable, of the double chloroginate with a bitter after taste, so unstable in the presence of oxygen, and, finally, of the aromatic essences? We hope that our learned practitioners will enlighten us on this point.

But already they have taught us, and the experience of every day confirms it, that coffee, differing from the powerful alcoholic drinks and narcotic vapors which intoxicate and stupify the senses, seems to unite all that is agreeable in the sensations of both orders, exciting the intellectual faculties.

Supposing that the principal cause of the special effects of coffee does not reside in the agreeable, diffusible aroma, it cannot be doubted, at least, that this property has the greatest influence on the commercial value; for this value is fixed according to the greater or less power, and the sweetness of the aroma in each variety; now, if we were to admit for the ponderal quantity of the essence only two-thirds of the price of coffee, we should attribute to the principal essential oil the enormous value of 10,000 francs (£400) the kilogramme.

chemists employ for preparing ammonia. Perfectly dried hydrochlorate of methyla mine is mixed with twice its weight of quick lime, and the mixture is introduced into a long tube, closed at one end, so as to occupy half of it; the other half being filled with pieces of caustic potassa, a disengagement tube is adapted, which passes into a test glass filled with mercury. The tube is slightly heated, beginning with the closed end; the methylammoniac gas, displaced by the lime, is abundantly disengaged, and passes into the test glass filled with mercury.

Thus prepared, methylamine is a non-permanent gas. Towards 32° F. it condenses into a liquid of great mobility. Its odor is strongly ammoniacal. Its density was found to be 1-13; it is, therefore, rather more dense than the air. The number found by experiment is a few hundredths higher than the theoretical number, which is 1.075. This, doubtless, is owing to the gas being too near its point of liquefaction at the temperature of 87°, at which the experiment was made.

Methylammoniacal gas is the most soluble of all the gases at present known. At the temperature of 54° F. one volume of water dissolves 1,040 volumes; a higher temperature diminishes this solubility, as might be expected. At 87° F. water takes up only 959 times its bulk.

Like ammonia, it is instantly absorbed by charcoal.

Like ammonia, it instantaneously restores the color of reddened litmus, and gives very thick white fumes in contact with a stirring rod dipped in hydrochloric acid. Like ammonia, it absorbs its own volume of hydrochloric acid and half its volume of carbonic acid. It is distinguished from ammonia by the following property: in contact with a lighted candle it takes fire, and burns with a yellowish flame.

The composition of methylammoniacal gas is represented by the formula

C2 H5 N=4 vol.

C2H5 N+ PoC2 N Po + H3. The solution of methylamine possesses the strong odor of the gas itself. Its taste is caustic and burning.

Iodine, in re-acting on the solution of methylamine, is converted into a powder of a pomegranate red, and the liquor, which is scarcely colored, contains hydriodate of methylamine IH, C2 H5 N. The red insoluble compound which is thus formed is analogous to iodide of nitrogen.

The salts of magnesia, alumina, manganese, iron, bismuth, chromium, uranium, tin, lead and mercury are precipitated by methylamine as by ammonia.

The salts of zinc at first gives white precipitates, but they are re-dissolved in an excess of the re-agent.

The salts of copper are precipitated of a blueish white; an excess of the re-agent readily dissolves the precipitate, forming a liquor of a deep blue color.

The salts of c dmium, rickel, and cobilt, are precipitated by the solution of methylamine; an excess of the re-agent does not redissolve the precipitate.

Nitrate of silver is completely precipitated by methylamine; oxide of silver easily dissolves in an excess of re-agent. When this solution is left to spontaneous evaporation, a black body is precipitated from it, which is analogous to fulminating silver. This substance does not explode either by a blow or by heat. Chloride of silver dissolves in the solution of methylamine. Chloride of gold is precipitated of a brownish yellow; an excess of re-agent readily re-dissolves the precipitate, forming a liquid of an orange-red color. A concentrated solution of chloride of platinum gives, with methylamine, a deposit crystallised in orange-colored bracteæ, formed by the double hydrochlorate of methylamine and platinum.

PREPARATION AND PROPERTIES OF ETHYL

AMINE.

I obtained this base by decomposing the hydrochlorate of ethylamine by lime. The

eudiometrical analyses :

of methylamine. Only, as ethylamine condenses easily, and is liquid at the ordinary temperature, the disengagement tube was passed into a matrass surrounded with ice, or, better still, with a frigorific mixture.

The ethylamine liberated by a gentle heat distils, and condenses in the receiver.

In the state of purity, it is a light, very mobile, and perfectly limpid liquid. It boils at 64° F. When poured on the hand, it instantly volatilises, producing a sensation of intense cold. It gives out an extremely penetrating ammoniacal odor; its causti

C

On the approach of a body in combustion, ethylamine takes fire and burns with a blueish flame. It mixes with water in all proportions, disengaging heat, and giving a solution whose basic properties are exactly the same as those which I have pointed out in describing the character of methylamine. I have remarked, however, that the hydrated oxide of copper dissolves less easily in ethylamine than in methylamine.

Chloride of platinum is not precipitated by ethylamine.

When a solution of ethylamine is mixed with oxalic ether, the mixture very soon be. comes turbid; alcohol is formed, and very | fine crystals, of a compound which is to oxamide what ethylamine is to ammonia, are separated. It is ethyloxamide, whose composition is represented by the formulaC6 H6 N2 0%.

The composition of anhydrous ethylamine is represented by the formulaC4 H7 N,

which was deduced from the following analyses

I. 0 gr. 266 of matter yielded 0.523 carbonic acid, and 0 gr. 374 water. II. 0 gr. 284 of matter yielded 74 c.c. 7 nitrogen, at 58° F. and 746 m. 5 pressure.

III. 0 gr. 239 of matter yielded 64 c.c. 6 of nitrogen at 58° F., and at 0 m. 755 pressure.

These numbers give in hundredths :-
Experiments.

Theory.

54.3

15.5

Numerous experiments have proved the certainty with which the soluble salts of uranium detect the presence of phosphoric acid. The following two facts, proved a great number of times, will suffice to establish it :

1. 0.05 gr. of syrupy phosphoric acid, added to one gallon of distilled water, furnished with nitrate of uranium, aided by boiling, a very abundant precipitate; salts of soda, potassa, ammonia, lime, and magnesia (in the latter two cases the liquor was acidulated to keep it limpid), added to the liquor to be tested, did not prevent the formation of the precipitate; the same salts, added to the distilled water, did not precipitate the nitrate of uranium.

2. Phosphate of lime was dissolved in hydrochloric acid; the very dilute solution gave a very abundant precipitate.

The estimation of phosphoric acid in the soluble phosphates is very simple. A solution of nitrate of uranium is made, of which one cubic centimetre will precipitate 0·001 grs. of phosphoric acid: a known weight of the phosphate to be analysed is dissolved in a known bulk of distilled water, taking care to neutralise it; 50 cubic centimetres of this liquor are boiled in a small flask, and, by means of a graduated burette, the nitrate of uranium is poured in until no further precipitation takes place, taking care to boil for a few seconds after each addition of the test solution.

In an early paper I shall give a process of estimating the phosphoric acid in the insoluble phosphates by means of nitrate of uranium.

......309 31.3 31.2

ON THE QUALITATIVE AND QUANTITATIVE ANALYSIS OF PHOSPHORIC ACID.*

BY M. C. LECONTE.

THE investigation of phosphoric acid, by means of the re-agents hitherto employed, presents great difficulties.

Having put almost all the known oxides in contact with phosphoric acid, the phos

* Comptes Rendus, No. 3, July 16, 1849.

ON THE CONSTITUTION OF STYRACINE.*

BY DR. A. STRECKER.

A CERTAIN analogy between the constitution of styracine and that of the natural fats has been demonstrated, and is the more worthy of attention as no acid corresponding to cinnamic acid has hitherto been discovered in nature in such conjugate union: nor, ex

cept the alcohols of the series C2n H2 (n + 1) O2, which correspond to the acids C2n H2n 04, was even the occurrence of known. The conjugate compounds of glyglycerine in analogous combinations ever

* Annalen der Chemie und Pharmacie.

cerine with the fatty acids occurring in nature appear, however, according to Gerhardt, to differ from the conjugate alcoholic compounds, as well as from the compounds of glycerine artificially prepared, inasmuch as they are decomposed, absorbing 6 eqs. of water, into 2 eqs. acid, and 1 eq. glycerine (C6 H8 O6); but this cannot be regarded as perfectly established, owing to the difficulty of obtaining these compounds pure, which is augmented by their general high atomic weights. They differ from the natural ethers, inasmuch as the latter furnish in decomposition only 1 eq. acid to 1 eq. alcohol, 2 eqs. of water being assimilated. The artificial compounds of glycerine which correspond to the acid ethers,, furnish, like them, 2 eqs. acid, and 1 eq. glycerine, 2 eqs. water being assimilated.

Regarded in this light, styracine, although closely approximating to the fats, seems to be more intimately related to the conjugate alcoholic compounds, amongst which spermaceti, and, according to Brodie, one constituent of wax, should be included.

The formula of styrone propounded by Dr. Toël not having been controlled by a determination of its atomic weight, we may indicate for this body other formulae, likewise in accordance with the composition found. I think I have succeeded in finding a formula for styrone, which has the power, in common with that of Dr. Toël, of accounting for the constitution of the compounds, but is preferable from its greater simplicity. My formula for styrone is C18 H10 O2, which requires, in 100 parts:

79.8 80.2 80.6

Calcu- Found. Toël. lated. Carbon.. 80-62 Hydrogen 7.45 Oxygen 11.93

7.6 7.7 7.6 12.6 12.2 11.8

Styrone might, perhaps, be regarded as the hydrate of an oxide (C18 H9), and its constitution would then be represented by (C18 H9) O + HO.

Setting aside all theoretical views concerning the alcohols, styrone stands, according to the foregoing formula, in the same relation to cinnamic acid as vinous alcohol to acetic acids, ethal to cetic (ethalic) acid; or, to express it in a few words, styrone is the alcohol of cinnamic acid :—Styrone= C18 H10 02-H2+02=C18 H8 04-cinnamic acid. Styrone contains 2 eqs. more hydrogen and 2 eqs. less oxygen than cinnamic acid, as in the case of all other known alcohols.

PROPORTION OF LIME IN LIME WATER.*

BY M. WITTSTELN.

AcCORDING to this chemist, 732 parts of cold water dissolve one part of anhydrous lime. The experiments to determine the solubility of lime in boiling water gave no satisfactory result. Three experiments gave respectively 1495, 1570, and 1311 parts of boiling water to one part of anhydrous lime. The carbonate of lime which is separated from lime water by exposure to the air is the neutral carbonate, Ca O, CO2.

COMPARATIVE STUDY OF THE AURIFEROUS SANDS OF CALIFORNIA, NEW GRANADA, AND OF THE OURAL.†

BY M. DUFRENOY.

THE French Consul at Monte Rey has forwarded to the Minister for Foreign Affairs a collection from the gold workings in California; a portion of this collection has been sent to the Ecole des Mines, and I have had an opportunity of examining it: it comprises :

* Buchner's Repertorium. † Comptes Rendus, No. 8, Aug. 20, 1849.