298 VIII. ACIDS.— Citric. 



Spirit of rye bread, Spiritus acidus panis secalincE. Cut 

 rye bread in slices, fill a retort with it, distil, rectify the aqueous 

 liquor. Used to extract the colour from garnets, and other stones, 

 which it does quicker than any other acid. 



Flowers of benjamin, i^/ores benzoini, Flares henzoes, Acidum 

 henzoicum. Melt benjamin with a very gentle heat in a glazed 

 earthen pot, to the neck of which a paper cone or chamber 

 is annexed ; if the flowers are tinged with oil, press them between 

 bibulous paper, mix with white clay, and sublime again : lb. j of 

 benjamin yielded 3ij of flowers. 



Scheele's benzoic acid. Benjamin lb. jss, lime jiiij ; rub 

 together, boil in water 1 gall., decant, boil the sediment in water 

 lb. iiij ; decant, mix the two liquors, and boil down to a half, filter, 

 add muriatic acid as long as any thing is thrown down, decant, 

 dry and sublime the flowers: lb. j of benjamin yields 5j Svj 3ij 

 of flowers. 



Green's benzoic acid. Benjamin 5xxiv, subcarb. of soda 

 5viij ; rub together, boil in water lb. xvj, strain, boil the grounds 

 in water lb. vj, strain, mix the two liquors, boil to lb. ij ; filter and 

 precipitate with dilute sulphuric acid q. s. ; dissolve the precipi- 

 tate in boiling water, strain and crystallize ; lb. j benjamin yielded 

 5j ^j '^j ^f flowers. Obtained also from the urine of neat cattle 

 and horses : a manufactory of sal ammoniac, near Magdeburgh, 

 which uses urine, is able to supply flowers of benjamin by the 

 cwt. Expectorant ; used in chronic coughs, gr, x to 5ss. 



Concrete acid of lemons, White citric acid, Acidum citri- 

 cum, Acidum citricum crystallis concretum. Saturate lemon or 

 limejuice with powdered chalk, wash the sediment with cold water 

 and dry it ; each gallon of lemon juice forms 8 oz. l-4th to 12 oz. 

 3-4ths of this citrate of lime : upon this powder pour dilute sul- 

 phuric acid fl. 3ix to each 3 of chalk previously used ; or, if the 

 imported citrate of lime is used, 151b. will require 40lb. of a spirit 

 of vitriol, whose specific gravity is 1*15 ; strain through a cloth 

 and expose the liquor in shallow vessels, that it may crystallize by 

 spontaneous evaporation : an agreeable acid, cooling, and anti- 

 septic; 3SS in water 3J, is equal to lemon juice. Gr. xxvj satu- 

 rate subcarb. of potash gr. Ixj, or subcarb. of ammon. gr. xlij, or 

 magnesia alba gr. xl. 



Brown citric acid. The first crop of crystals when evapo- 

 rated by heat ; sold cheaper. 



Crystallized acid of tartar, Acidum tartari crystallisatum. 

 Cream of tartar 30 oz., boil in water 2 gall. ; add chalk till it 

 ceases to effervesce (about lib.), let it settle, strain, wash ; to the 

 sediment add oil of vitriol \2 oz., diluted with water 1 gall, stir, 



