from uohich " hidian Yellow " is maniifactured. 325 



I. 0*4194< substance dried at 212° F. and burned with oxide 

 of copper, gave l'04-5 carbonic acid and 0*1357 water. 



II. 0-375 gave 0*9339 carbonic acid and 0*1222 water. 



III. 0*318 burned with chromate of lead gave 0*796 car- 

 bonic acid and 0*107 water. 



100*00 100*00 100*00 1425 100*00 



These numbers correspond pretty closely with the formula 

 Cl3 H4 04. The substance is pretty difficult to burn, which 

 accounts for the deficiency of carbon in the first two analyses, 

 when oxide of copper was employed. I propose the provi- 

 sional name purrenone for this body, which in the mode of its 

 formation somewhat resembles alizarine, both being neutral 

 bodies, obtained by subliming feebly acid colouring matters. 

 Purrenone may also be procured by subliming the lead salt. 

 When burned on platinum foil it leaves no residue. 



When purreic acid is treated in the cold with nitric acid of 

 ordinary strength, it dissolves apparently without decomposi- 

 tion. With the assistance of heat it is rapidly decomposed 

 with the abundant evolution of nitrous gas. When the 

 nitric acid is driven off by gently evaporating to dryness on 

 the water-bath, a crystalline acid is obtained, which is much 

 more soluble than the purreic acid, and stains the skin or paper 

 of a deep yellow colour. When its concentrated solutionis 

 neutralized by potash, a reddish-yellow salt precipitates, 

 crystallized in pretty large needles. When heated it deto- 

 nates, and thus appears to contain nitrogen. From want of 

 material I was unable to continue its investigation, but I may 

 probably resume it at a future time. 



When purreic acid is boiled with peroxide of manganese 

 no action takes place, but on the addition of sulphuric acid it 

 is decomposed with the production of formic acid. When pur- 

 reic acid is strongly heated with solid potash, it dissolves with 

 a bright scarlet colour; on neutralizing with an acid the colour 

 disappears and the purreic acid is precipitated, converted ap- 

 parently into a resinous matter. 



I would conclude for the present by observing, that notwith- 

 standing all the reports to the contrary, it appears highly pro- 

 bable that the purree of commerce is the juice of some tree or 

 plant, which, after it has been expressed, has been saturated 

 with magnesia and boiled down to its present consistencct 

 Glasgow, September 19, 1844. 



