VIII. ACIDS.— Sulphuric. 307 



Phosphoric acid, Acidum phosphoricum. Bone ash in fine 

 powder 48 oz., oil of vitriol 26 oz., water 16 oz. ; boil for two 

 nours in a tin vessel, strain, add fresh water until all the acidity is 

 extracted, mix the waters and boil to 36 oz., at first in a tin, and 

 then in a porcelain vessel. Add subcarbonate of ammonia water 

 as long as any sediment falls; filter, evaporate, remove into a 

 porcelain crucible, and reduce it by evaporation and fusion in 

 silver vessels to a clear glass, which weigh and dissolve in six 

 times as much water. 



2. By adding phosphorus gradually to nitrous acid in a pierced 

 retort ; when all the phosphorus is dissolved, the remaining nitrous 

 acid is distilled off; used in caries of the teeth and bones, gutt. xv 

 to xl, in water 3ij every two hours ; it has been also employed 

 externally in caries ossium, compresses moistened with the acid 

 diluted with eight parts of distilled water being applied over the 

 ulcers, under which the bone was carious. 



German oil of vitriol. Oleum vitriolif Spiritus vitrioli 

 [brtis, Acidum sulphuricum Germanicum, Calcine copperas to 

 redness, distil in small charges for about 18 hours, although it 

 will continue to emit vapour for 10 days. Boerhaave from 81b. 

 copj^ras calcined to 5lb., in 2 retorts, obtained 21 oz. of thick 

 black smoking oil, and 52 oz. of light powdery colcothar were left, 

 8 oz. passed off uncondensed. Bernhard from 6 cwt. calcined to 

 a yellowish red, distilled apparently in 12lb. charges, the phlegm 

 collected in dishes until very acid, and white vapours began to 

 appear, and then '\\h. put into each receiver, which were luted on, 

 obtained only 64lb. 



Nordliausen oil of vitriol^ Acide fumante de Nordhausen. From 



)j)peras calcined to redness, distilled in 3\h, charges in earthen 



I ucurbites set slanting, to get out the colcothar without disturbing 



fhem, the phlegm allowed to drop into a dish until white vapours 



upear very copiously, receivers then applied and luted with i;\h, 



iter in each in the first distillation : 3 charges of each retort are 



>tilled into each receiver bef(3re the acid is poured out; black, 



■ ,^r. I'O, or 68 deg. Baumc ; by exposure to air, 



to smoke, and l)ec()mes similar to the acid ob- 



iit'cl from sulphur. Dissolves a larger quantity of itidigo than 



• ' acid from sulphur; the solution rccjuircs no heat, and is of a 



uitiful purple colour. From Nordhausen in Saxony, also from 



<'y\ in Bohemia, where a manufactory of it has been established 



')m time immemorial. Used in dyeing. 



^hite tnwkijuf guluhuric acid. Copperas calcined to redness 

 lb., distil and receive the vapours in oil of vitriol from sulphur 

 lb.; produces lOlb. of smoking acid, perfectly similar to the 

 >rdhausen except in colour. 



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