Substances of Organic Origin, No. IV. Retin Asphalt. 563 



of oxide of silver respectively. According to theory we 

 should have 



C21H14O3 = 2079-8914 = 58-895 

 AgO = 1451-607 = 41-1()5 



I 3531-4.984 lOO'OOO 



This exhibits a considerable difference from the experi- 

 mental result. The third portion analysed was precipitated 

 by a sohition of the acid in a?ther; it is quite possible, there- 

 fore, that the error may be owing to the presence of reduced 

 silver. At ail events the approximation is sufficiently close 

 to show that the equivalent of the acid is represented by the 

 same multiple of the elements as we have above deduced from 

 direct analysis. 



Retinate of Lead. — An alcoholic solution of acetate of lead 

 gives with one of retinic acid a dark brown precipitate, which 

 on drying is of a light umber colour. Heated in the air it 

 behaves like the silver salt, and when burned leaves oxide of 

 lead mixed with a greater or less portion of metallic lead. 

 It is nearly insoluble in alcohol, and therefore may be fully 

 washed; but partly owing to the impossibility of burning it 

 without loss of lead by volatilization, or to some other cause 

 which has escaped me, I have not been able with specimens 

 of this salt prepared by different methods, to obtain nearer 

 approximations to the theoretical per centage than those fur- 

 nished by the analysis of the silver salt. It is unnecessary, 

 therefore, to insert the numerical results. 



Retinate of Lime is precipitated very sparingly and of a 

 brown colour, when ammonia is added to the mixed alcoholic 

 solutions of retinic acid and chloride of calcium. It is sparingly 

 soluble in water, giving a pale yellow solution : when heated 

 in the air it blackens, but does not melt, and at a red heat 

 leaves carbonate of lime. Dried at 300° Fahr. 0*524 grs. 

 left 0096 carbonate = 18*32 per cent., or 10*312 of lime. 

 This would indicate a sesqui-salt, composed of 



Per cent. 



calculated . By experiment. 

 li(C2iHi4 03) = 3119*837 = 89*758 = 89*788 

 1 CaO = 356*019 = 10*242 = 10-312 



3475*856 100- 

 On a single result however, and obtained from so small a 

 quantity, no great reliance ought to be placed. 



The retinates of baryta and strontia may be obtained by 

 digesting the caustic earths in alcoholic or aethereal solutions 

 of the acid. It is difficult, however, by this method fully to 



2 Z 2 



