be attached to the spiral, as shewn in the plan. One of the most simple, and in many instances a sufficiently perfect method, is, to fix each of the pullies to the end of an elastic piece of timber supported in the middle, and the opposite end attached to a weight a little superior to the weight of the full corf and greatest length of rope, each end being properly tapered.

As it is ineligible to alter materially the line of suspension of corves or buckets, it is necessary, if much vertical motion be intended to be allowed to the pullies, that the rope be prevented getting out of its vertical position; which may be done by a roller or sheave below the pullies, as shewn by x, Fig. 5; and with this precaution the outer ends of the elastic beams may either lift a series of weights, or a weight on a spiral.

In any of the preceding instances the rope or chain which lifts a series of weights, or one weight with the intervention of a spiral, may be attached to a sheave or barrel, connected with a loaded lever on the same axis; in which case the stress on the chain or rope would be increased or diminished according as the lever became more horizontal or vertical during the motion of the barrel or sheave, which generally should be limited to less than a quarter of a circle. Also the purpose of producing a diversity of resistance on the pit-ropes, with uniformity of weight of counterbalance, may be obtained, by placing the two wheels o and x, in Fig. 4, at a considerably greater distance from each other than the diameter of the wheel t, on which the weight is suspended; as by this means the two parts of the rope which raise the wheel will pull more and more obliquely as the latter rises.

In witness whereof, &c.

Specification

Specification of the Patent granted to JOSEPH ASTLEY, of Borrowstounness, in Scotland, Chemist; for Improvements in the Manufacture of Sal-Ammoniac..

Dated July 28, 1807.

To all to whom these presents shall come, &c.

Now KNOW YE, that in compliance with the said proviso, I the said Joseph Astley do hereby declare, that the nature of my said invention is described in manner following; that is to say I prepare,the salt called muriate of magnesia, or the muriate of alumine, or one or other of the metallic muriates, or any of the combinations of muriatic acid from which the acid is capable of being disengaged by heat. What I commonly employ is the muriate of magnesia, which may be procured in different ways, and very easily and economically from the mother liquor of the salt-pans, called bittern or salt-oil; the other salts contained in this being separated by evaporation and crystallisation.

I use the muriate of magnesia prepared by this or by any other process, or any of the other articles above-mentioned, either in a liquid or in a solid form. In the former way I cause animal substances of all kinds, or such vegetable or mineral substances as afford ammonia or volatile alkali by distillation, to be impregnated with liquor holding any of the said salts in solution; which liquor I use in proportions varying according to the particular kind of salt employed, the degree of concentration of the liquor, and the nature of the animal or other substances to be impregnated, the object being to obtain the acid and alkali developed in the subsequent operation in proportions approaching as nearly as possible to mutual saturation.

I afterwards dry the animal or other substances thus impregnated on a heated floor or otherwise, and either distill

them

them by the heat of a furnace in a retort or still, with one or more receivers adapted to collect the products, or else burn them in a kind of furnace or kiln (which may be variously constructed), the products of the combustion being collected in chambers or receivers adapted to the purpose, which chambers or receivers must have an opening or vent to maintain the current of air necessary for the combustion.

The previous drying is not an essential part of the process, and in some cases may be dispensed with, though it will generally be found expedient.

1

Where I use the salt in a solid form, that is, either crystallised or dried by evaporation, the process is merely to mix it in such state with the animal or other substances, and proceed as above. But I find that the object is effected more easily and completely by using the salt in the state of

solution.

Or, instead of impregnating the animal or other substances themselves with any of the saline matters above described, I cause substances of any description whatever, (provided there be nothing in their nature rendering them chemically or mechanically unfit to serve as vehicles for such purpose) to be impregnated with such saline matter, and treated as above described along with the animal or other substances: the fundamental object of all these processes being to present the acid and alkali to each other in their nascent state, as they are respectively developed from the said saline matters and the animal or other substances by heat-by which means we obtain, on the one hand, a more complete decomposition of the said salts by help of the divellent affinity of the ammonia; and we prevent in a great measure on the other hand the destruction of the alkali by combustion, which would otherwise occasion great loss in the burning of the materials. In all the processes here described the product is the same, being muriate of ammoVOL. XII.-SECOND SERIES.

Kk

nia,

nia, or sal-ammoniac, partly dry and partly in solution, which is afterwards to be crystallised and sublimed according to the ordinary processes, or which may be used for some purposes without undergoing these subsequent operations.

It may be proper to state that I do not here lay claim to the exclusive privilege of procuring muriatic acid from the salts above-mentioned by distillation, as it has been long known to chemists that several of them are decomposable by heat. My claim is to the modes of effecting this decomposition as here explained, which will be found to possess, besides the advantages already mentioned, that of avoiding the inconveniencies with which the operation of distilling the muriatic salts in question (particularly the muriate of magnesia) by themselves is always attended.

In witness whereof, &c.

Specification of the Patent granted to JOHN PHILLIPS, of East-Stonehouse, in the County of Devon, Stone-mason and Sculptor for Improvements in the Construction of TinderBoxes, whereby they will be rendered more useful than they at present are, part of which may be applied to other useful Purposes.

Dated February 12, 1806.

With a Plate.

To all to whom these presents shall come, &c. NOW KNOW YE, that in compliance with the said proviso, I the said John Phillips do hereby declare that my said invention is described and ascertained by the drawings and descriptions thereof hereunto annexed.

EXPLANA.

EXPLANATION OF THE DRAWINGS.

Fig. 1. (Plate XI.) represents the tinder-box, the bottom of which is made as these articles generally afe, except the steel, which is here fastened to the damper as at A.

Fig. 2 shews the top of the tinder-box, which may be a little turned up at the edge, as at e e, Fig. 4, and to which is fixed one, two, or more wires, or other proper substance, as may be found convenient, as BB, Fig. 3, which slide up and down in tubes attached to the outside of the hollow cylinder or other formed screen made of glass, horn, or other transparent substance, as C C, Fig. 3, and N N N N, Fig, 4. A bottom of tin or other substance must be attached to the same, which must be perforated as at D, Fig. 4, so as to let a candle go through the same, and rest on the top of the tinder-box at E, Fig, 4: which candle may be there confined by one, two, or more points, similar to what is called a save-all, or by a short socket, &c. The transparent screen may have a door, as shewn at F, Fig. 4, and at G, Fig. 3; or the door in the side may be omitted as at Fig. 7, and then two hollow transparent screens may be applied as PQ, the one smaller than the other, connected at the bottom so as to hold water, spirits of wine, or any transparent liquid, which will cause when the candle burns within, as at T, a steady and good light. In consequence of the transparent screen being attached to the top of the tinder-box or bottom of the candlestick, with a hole through the bottom of the same, the size of the candle to be burnt therein, as at D, Fig. 4, and U, Fig. 7, the candle is prevented from catching or setting any thing on fire which may be placed near it, and a long candle may be burnt therein by means of the wires sliding in the tubes, as at Figs. 3, 4, and 5; and the tubes S S S sliding on the wires W W W, Fig. 7, the upper part of the candle