2^8 Kt^iu Vuhllcations. 



aJI other artlfts who am In the habit oP empJoying tlufe 

 fiibfVancc5. In the firft part of this work I have already trivvii 

 riik^ for diicovering fuch ad ii Herat ions ; and to what has been 

 faid, I apprehend it is only neccflary to add the direftions of 

 Air, Kirwan, intended to cftl'6l the fame end, but differing in 

 the mode. They are tranfcribed iVoni his paper cntitlefj 

 * ilxperiments on the Alkahnc Siibliances .«ifed in Bleach-' 

 ing-.' — Sec Tran^a<!^lioDs of the Iriih Acadeniy for 1789. 



*' To difan-er whether any quantity of fixed alkah worth 

 attention cxifts in any fahne compound, diflolveone ounce oi 

 it in boiling water, and into this fohition let fall a drop of a 

 fc^utlon of fublimatc corrofive; this will be converted into a 

 brick colour, jf an alkali be pref^nt, or into a brick colour 

 l»ixcd with yellow, if the fubltance tried contains lime. 

 ' " But the fubftances vifcd by bleachers beincr always im- 

 piregi^ated with an alkali, the above trial is in general fupcr- 

 f^uous, except for the purpofe of detecting Ihne. The qiian^ 

 tity of alkali is therefore what they fliould chiefly be foli-r 

 citons to determine, and for this purpofe, 



<' I ft. Procure a quantity of alum, fuppofe one pound, re-t 

 ^uce it to powder, waili it with cold water, and then put it 

 mto a tea-pot, pouring on it three or four times its weight of 

 lioiling water. 



'^ adly. Weigh an ounce of the afli or alkaline fubftance 

 tolixe tried, powder it, and put it into a Florence flafk with ontj 

 pound of pure water (common water boiled for a quarter of an 

 hour, an<l afterwards filtered through paper, will anfwer), if 

 the fubftance to be examined be of the nature of barilla, of 

 potafli ', or half a pound of water if it contain but little earthy 

 matter, as pearl-afli ; let them boil for a quarter of an hour : 

 whencool, let the fblution be filtered into another Florence flafk, 



" 3dly. This being done, gradually pour the folution of 

 af[«m, hot, into the alkaline folution alfo heated; a prccipi-, 

 tation will immedigtely appear; {hake them well together^ 

 'anJ let the effervefcence, if any, ceafe before more of the 

 aluminous folution be added ; continue the addition of the 

 almn until the mixed liquor, when clear, turns fyrup of vio- 

 jels-, or pr.per tinged blue by radifhcs, or by litmus, rccj'* 

 th«n pour the }i^uor and precipitate on a paper filter placed 



