ALCOHOL 55 



According to Groning's researches, the preceding temperatures of the alcoholic 

 vapours correspond to tho accompanying contents of alcohol in per-contage of volume 

 which are disengaged in the boiling of the spirituous liquid. 



Groning undertook this investigation in order to employ the thermometer as an 

 alcoholometer in the distillation of spirits; for which purpose he thrust the bulb of the 

 thermometer through a cork inserted into a tube fixed in the capital of the still. The 

 state of the barometer ought also to be considered in making comparative experiments 

 of this kind. Since, by this method, the alcoholic content may be compared with tho 

 temperature of the vapour that passes over at any time, so also the contents of the 

 whole distillation may be found approximately ; and the method serves as a convenient 

 means of making continual observations on the progress of the distillation. 



From the mean of a great many experiments, Dr. Uro drew up the following Table, 

 which shows the boiling point of alcohol of various specific gravities : 



Density of the Vapour. One volume of alcohol yields 488'3 volumes of vapour 

 at 212 F. The specific gravity of tho vapour, taking air as unity, was found by 

 Gay-Lussac to be 1-6133. fits vapour-density, referred to hydrogen as unity, is 

 13-3605?] 



Spirituous vapour passed through an ignited tube of glass or porcelain is converted 

 into carbonic oxide, water, hydrogen, carburetted hydrogen, olefiant gas, naphthaline, 

 empyreumatic oil, and carbon ; according to the degree of heat and nature of the 

 tube, these products vary. Anhydrous alcohol is a non-conductor of electricity, but 

 is decomposed by a powerful voltaic battery. Alcohol burns in the air with a blue 

 flame into carbonic acid and water ; the water being heavier than the spirit, because 

 46 parts of alcohol contain 6 of hydrogen, which form 54 of water. In oxygen the 

 combustion is accompanied with great heat, and this flame, directed through a small 

 tube, powerfully ignites bodies exposed to it. 



Platinum in a finely divided state has the property of determining the combi- 

 nation of alcohol with the oxygen of the air in a remarkable manner. A ball of 

 spongy platinum, placed slightly above the wick of a lamp fed by spirit and commu- 

 nicating with the wick by a platinum wire, when once heated, keeps at a red heat, 

 gradually burning tho spirit. This has been applied in the construction of the so- 

 called ' philosophical pastilles ; ' eau-de-cologno or other perfumed spirit being thus 

 mado to diffuse itself in a room. 



Mr. Gill has also practically applied this in the construction of an alcohol lamp 

 without flame. 



A coil of platinum wire, of about the one-hundredth part of an inch in thickness, 

 is coiled partly round the cotton wick of a spirit-lamp, and partly above it, and the 

 lamp lighted to heat the wire to redness ; on the flame being extinguished, the alcohol 

 vapour keeps the wire red hot for any length of time, so as to be in constant readiness 

 to ignite a match, for example. This lamp affords sufficient light to show the hour 

 by a watch in the night, with a very small consumption of spirit. 



This property of condensing oxygen, and thus causing the union of it with com- 

 bustible bodies, is not confined to platinum, but is possessed, though in a less degree, 

 by other porous bodies. If we moisten sand in a capsule with absolute alcohol, and 

 cover it with previously heated nickel powder, protoxide of nickel, cobalt powder, 

 protoxide of cobalt, protoxide of uranium, or oxide of tin (these six bodies being 

 procured by ignition of their oxalates in a crucible), or finely powdered peroxide 

 of manganese, combustion takes place, and continues so long as the spirituous vapour 

 lasts. 



Solvent Power. Ono of the properties of alcohol most valuable in tho arts is ite 

 solvent power. 



It dissolves gases to a very considerable extent, which gases, if they do not enter 

 into combination with the alcohol, or act chemically upon it, are expelled again on 

 boiling the alcohol. 



Several salts, especially the deliquescent, lire dissolved by it, and some of them 



