from *which " Indiaii Yellow " is manufactured. 323 



II. 0-4294 gave 0-866 carbonic acid and 0*1706 water. 



III. 0-437 gave 0*882 carbonic acid and 0*175 water. 



• Calculated numbers. 



Atom. Per cent. 



Carbon 20=1500 55-30 

 Hydrogen 9= 112 4-20 

 Oxygen 11 = 1100 40-50 



100-00 100-000 100-00 2712 100-00 



These analyses appear therefore to give C20 H9 Oil as 

 the formula of the acid to which I shall give the provisional 

 name of the purreic. It is but little soluble in cold water, but 

 dissolves pretty readily in boiling water, from which it is de- 

 posited in long slender silky needles of a faint yellow colour. 

 The alkalies, and especially ammonia, immediately change its 

 solution to a fine deep yellow colour. The acid is exceed- 

 ingly soluble in hot spirits of wine, which is its best solvent. 

 When water is added to the solution, the greater portion of 

 the acid is immediately deposited in small crystals. It also 

 dissolves to a considerable extent in aether, and is deposited in 

 needles arranged in stars on the evaporation of the liquid : 

 its taste is at first sweetish and then slightly bitter. In ap- 

 pearance it has a considerable resemblance to berberine, but 

 has rather a lighter colour. The quantity of acid in the crude 

 purree is exceedingly great, amounting, I should think, to 

 nearly half its weight. Purreic acid was also carefully exa- 

 mined for nitrogen, but not a trace of it could be detected. 

 The acid does not precipitate the salts of silver, lime, barytes, 

 strontian, or magnesia, but it gives a deep yellow precipitate 

 with acetate of lead. Its combinations with the alkalies are 

 very soluble and slightly crystalline. The saturating power 

 of the acid appears to be very feeble, as a few drops of an 

 alkali added to a strong solution of the acid give it an alka- 

 line reaction. When purreic acid is neutralized with an 

 alkali, it gives bright yellow precipitates with solutions of most 

 of the bases, as silver, lime, barytes, magnesia, &c. With 

 protosulphate of iron it gives a deep green precipitate; these 

 precipitates are all very flocculent and pretty soluble, so that 

 it is dijfficult to obtain them of an uniform nature. The salt 

 which I employed to determine the atomic weight was the 

 lead compound, and even with this I found considerable diffi- 

 culty in obtaining satisfactory results. The lead salt was 

 prepared by adding an alcoholic solution of acetate of lead to 

 a hot solution of the acid, also in alcohol. The salt falls as 

 an orange yellow, somewhat gelatinous precipitate. It was 

 boiled repeatedly with spirits of wine, in which it is nearly in- 



Y2 



