A L C 



A L C 



by a very (rontle waimth. The fait is left moid in the ftill, 

 and comaiiis inucli of the water of the fpirit cinploycd. 

 Some recommend burnt alum in the room of ialt, but the 

 beft addition is very diy, hot, carbonated alkali. A highly 

 dcphlegmated alcohol may be prepared in this method with- 

 out the intermediate proctfs of dilliUation, only then the 

 fpirit will be of r rcddifh colour, and will contain that fmall 

 portion of cauftlc alkali which is always mixed with eom- 

 r.ion carbonated potafli, and which is foluble in ardent fpirit. 

 Tjie following is Boerhaavc's procefs : " Take a clean glafs 

 " body containing common fpirit of wine, and add thereto 

 •' one-third of its weight of pure and dry potafh, (carbo- 

 *' nated potafli), which immediately falls to the bottom. 

 " Shake the glafsj, and the fait direftly grows moi!l and 

 " begins to diffolve at the bottom, whilll a red thin liquor 

 " floats above it ; the moa' the velTcl i'A fhaken, the more 

 ♦' liquid is the lower part of the fait, and the more dillinClly 

 " feparated from the upper liquor, nor is it ever pofTible to 

 " mix them together, but upon relling they will immediately 

 •' feparate into two liquors." 



This procefs may be continued, he adds, by decanting 

 carefully the upper of the two liquors, (which is the al- 

 cohol reddened by a little cauftic alkali that it holds dif- 

 folved) and adding to it more carbonated alkali, till the 

 portion lad added will no longer become wet on fliaking, 

 a fign that the alcohol is as fully deprived of water as it 

 is capable of being made by means of alkali. As a proof of 

 the high dephlegraation of the fpirit by this method, it 

 may be obfer\-cd, that if a drop or two of water be added 

 to alcohol in which fait of tartar has long remained dry, 

 the alkali immediately becomes moift, and appears to run 

 unftuous from the fides of the veffcl. 



If the alcohol be (hjlilkd off the alkaline Mt with a 

 gentle heat, the firll part which comes over will be about the 

 ipecific gravity of 0.813 to 0.815, at the temperature of 

 60°, and this is as high a degree of purity as it has 

 been brought to in the accurate experiments made in this 

 country, by Dr. Blagden and others, for the purpofe of 

 afcertainlng its fpeeific gravity. (See GRAViTvy/'rt/yfc.) 



M. I^owitz, however, allerts, that he has brought al- 

 cohol to the fpeeific gravity of 0.791, chiefly by adding, 

 before dillillation, a ver/ large quantity of alkali fo as al- 

 mofl entirely to abforb the fpirit. 



After difiillation, the wet alkaline fait which is left may 

 be dried, and again ufed for the fame purpofe ; but Boer- 

 haave afferts, that after repeating the ufe of the fame 

 alkali for a number of times, it becomes changed in its 

 nature, and unfit for the purpofe. This would imply a 

 decompolitlon of the alcohol, which deferves to be further 

 examined. 



Various tefts have been devifed for afcertaining the 

 purity of alcohol, and the proportion of water which it 

 contains. A fpirit, which is very free from water will, 

 when fet fire to, burn away without leaving any refidue ; 

 if it is of moderate ftrength it will burn for a certain time, 

 and then become extinguilhed, and leave a portion of wa- 

 ter more or lefs confiderable, according to the degree of 

 dephlegmation ; if, on the contrary, it is very weak and 

 watery, it will not kindle at all. This tell, however, is 

 by no means accurate, fince the heat of the burning fpirit 

 will drive off part of the water which lliould be left in the 

 refiduum. Another tell is, to drop a fmall quantity of 

 fpirit on a fmall heap of gunpowder and kindle it. The 

 fpirit burns quietly on the furface of the powder till it 

 is all confumed, and the lafl portion fires the powder if 

 the fpirit was pure, but if watery, the powder becomes 

 too damp and will not explode. This tell. alfo. is very 



inaccuratf ; for if the powder be drenched with even 

 a llrong Ipirit, it rer.uiins too damp to be fired ; and if 

 it be only barely moitktn.'d, any fpirit that will burn will 

 inflame it. A better tilk is, as we have mentioned, to 

 fliake the fpirit in a phial with fomc dry carbonated alkali ; 

 but the mod accurate of all is to afeertain its fpceilic ^r^- 

 vity, and compare it with the denfity of known qiumtitics 

 of alcohol and water, jireviotifly mixed for the purpofe 

 of giving a ilandard of eomparifon. The very exteiifivc 

 and accurate labours on this fubiedi, conduelcd by Bcaumc, 

 Blagden, Oouvenain, and other eminent fcientilic men, be- 

 long with more projiritty to the fubjcCt lA fpicifu Gravity, 



It remains for us to mention the chemical nature of al- 

 cohol, and the appearances which attend its deconipofition. 

 The remarkable circumftance of a vegetable producfl burn- 

 ing away, without the finalleft trace of fmokc or fuliginous 

 vapour of any kind, had long engaged the attriitiim of 

 chemills. Junker and Boerhaave threw much light on 

 the fubjedl by remarking, that the produft of the corn- 

 bullion of alcohol was always a quantity of pure water ; 

 and this faft was more fully illullrated by the experiments 

 of the illudrious Lavoilier. l"hc ready evaporation of 

 alcohol, and the eafe with which its vapour will fill a large 

 veficl, renders it a dangerous experiment to fubmit a con- 

 fiderable quantity at once to combullion, in oxygen gas 

 confined in any veflel, but this difficulty was furmountcd 

 in an ingenious manner. His firll experiment was fimply 

 to afcertain the quantity of water yielded by the coin- 

 bullion of a given weight of alcohol. This was performed 

 in the follov.ing apparatus, contrived by M. Mcufmier. 

 See Plates of Chi; MI sTRY, fig. 10. 



E F is a worm, contained in the cooler A BCD. To 

 th.e upper part of the worm E, the chimney G H is 

 fixed, which is compofed of two tubes, one within the 

 other, the inner of which is a contin.iation of the worm, 

 and the outer one is a cafe of tin-plate, which fuirounds 

 it at about an inch diftance, and the interval is filled witli- 

 fand. At the inferior extremity K of the inner tube, a 

 glafs tube is fixed, to which is adopted the argand lamp 

 I^ M, for burning alcohol. 



Things being thus difpofed, and the lamp being filled 

 with a determinate quantity of alcohol, it is fet on fire ; 

 the water which is formed during conihuftion, rifes in 

 the chimney K E, and being condenfed in the worm^ 

 runs out at its extremity F, into the bottle P. The ufe of 

 the outer tube G H, and of the fand between it and the 

 inner tube, is to prevent the latter which pr(;cetds from 

 the worm, from being cooled during combullion, whielr 

 would occafion the water, formed by the burning, to fall 

 back on the lamp inftead of paffing on into the worm. 



This apparatus though not perfect, has the advantage 

 of enabling the chemift to operate with larger quantities 

 than can be admitted in the more accurate experiments on 

 combullion, and by it, the above-mentioned chemifts were 

 able to eftabhlh the important faft, that the quantity of 

 water collected by the combuilion of alcohol very fciijibly 

 exceeils the quantity of the alcohol -which is confumed. The 

 produft of water mull vary according to the ilrcngth of 

 the alcohol, and the care of conducting the experiment ;. 

 but it is fo confiderable, that from fixtecn ounces of ar- 

 dent fpirit, Lavoifier obtained eighteen ounces and a half 

 of pure water. There is befides, however, a large quan- 

 tity of carbonic acid produced in this experiment whicli, 

 efcapes, and cannot be ellimated by this apparatus. Some 

 of this gas unites with the water which is collefted, and 

 cnufes it to precipitate lime-water. 



Having thus afcertaiiied in a general way the produdla 



