V. Table of the successive Strengths af Pyl-ozglii S'iiz.it9 COP responthkg to its successive Specfie Gravities wilh some In -trodtictory Observntioiis. By ANDREW UHE,M.D. F.R.S &* Read June 1 1841. HAVING been professionally employed by an eminent manufacturing chemist about eighteen months ago in experimental researches upon the above spirit the Aolzgeist of the Germans 1 found it necessary to construct the following table in order to ascertain the commercial value ofthe article at various densities. The principd use of wood-spirit as extracted by distilration from p~~rolignoiis acid OF from liquid pyrolignite of lime is for dissolving shell-lac and sancfarac into a varnish for stiffening the bodies of hats and rendering them impervious to water.Hats imbued with this varnish exhale in the hot apartments where the process is conducted the va- pours of the wood-spirit very copiously and thereby occasion a painful irritation to the eyes of the workmen. Some kinds of the spirit are much more iiijurious to the eyes and the health than others even when they have all been rectified to apparently the same pitch of purity and strength by the same operatioris. Ohe purpose of my researches was to cliseover Dr. Ure on Pyroxylic Spirit. the causes of these variations which affect the comfort of the operatives and another was to discover the causes of the variations in the solvent qualities of wood-spirit of the same strength by the hydrometer. Having hitherto but partially succeeded in the attainment of these two objects I shall not occupy the time of the Society at present with an account of the experiments made with that view but shall reserve them for a future communication.The researches of Berzelius Gmelin Weidmann Schwei- tzer Kane Liebig Dumas and Peligot concur to prove that the ordinary wood-spirit of commerce even in its most highly rectified state is not like spirit of wine merely an alcoholic liquor more or less diluted with water but that it consists of different compounds mingled together and very difficultly separable from each other. Wood-spirit xylite and mesite are three of these liquid compounds usually associated in pyroxylic spirit. When the conimon wood naphtha of the druggist is distilled three or four times from pulverized un-slaked quicklime by the heat of a water-bath the oily impu-rities and water are got rid of and an anhydrous fluid is obtained which is not liable to become brown on exposure to light like the ordinary wood naphtha and which does not become turbid or milky when mixed with water.This puri-fied spirit however still acts 3s painfully almost as the ori- ginal cruder article upon the eyes of the hatters as I ascer-tained by trial. One mode of separating mood-spirit froin xylite and mesite is founded upon the property possessed by wood-spirit of forming a compoiind with chloride of calcium not decomposable at the heat of boiling ~ater while similar coinpourids with xylite and mesite are decomposable at that temperature.I did not find that pyroxylic spirit was essen-tially improved as to its employment in the arts by being rectified by distillation from its combination with chloride of calcium. Methol is the name which has been given to the oil formed by the action of sulphuric acid upon wood-spirit xylite and mesite; and I believe the same oil is generated by the simple combustion of pyroxylic spirit ;for I have observed that when the pyroxylic spirit which has been treated with both quick- lime and chloride of calcium is burned in a platinum capsule till fully one-half be consumed the residuum becomes oily and opalescent. The spirit used for the construction of the following table was purified by distillation from pulverized quicklime arid was drawn over with the heat of a water-bath at such a tem-perature that its specific gravity at 60' was O9S136.When Mr. R. C. Canlpbell on the Fewocyanides. the specific gravity becomes 0.847 by the dissipation of the lighter spirit the boiling point is 145' Fahr. 1 believe that a usefiil criterion of the nature of pyroxylic spirit would be obtained by comparing its boiling temperatures at different degrees of density. To this point I shall also direct my further investigations. The temperature of the pyroxylic spirit when the specific gravities were taken was exactly 60' Fahr. @c. Grav Spirit per cent. )ver proof o Excise scale Qec. Grav Spirit per cent. Over proof 01 Excise scale. 08136 100.00 0821U 98-00 64.10 0.9032 68.50 13.1 08256 96.1 1 61.10 0.9060 67.56 11.4 08320 0.8384 9434 92-22 58.00 55.50 0.9070? 0.9116J 66.66 65-00 9.37 10 08418 9090 52-50 0.9154 63.30 4.80 08470 89.30 49.70 0.9184 61.73 2.10 0.85 14 08564 08596 87-72 86.20 84.75 47-40 44.60 42.20 09218 0.9242 60.24 58.82 Under proof.0.6 2.5 08642 8333 39.90 09266 57.73 4.0 0 8674 82.00 37-10 09296 56-18 7-00 0871 2 8064 35.00 0 9344 53-70 11.00 0.8742 79.36 32.70 0.9386 5 1-54 15-30 08784 78.13 30.00 0.94 14 50.00 17.80 0.8820 77.00 27.90 0.9448 47.62 20.80 08842 75.76 26.00 0.9484 46.00 25-10 08876 74-63 24.36 09518 43.48 28-80 08918 73.53 22.20 0.9540 4 1.66 31.90 0.8930 72.46 20.60 0-9564 40.00 34-20 0.8950 71-43 18.30 0.9584 38.46 35-60 0.8984 70.42 16.60 09600 37.11 38.1 0.9008 69.44 15.3 0.9620 55.71 40.6