32 REPORT — 1844. 



verted into a soluble viscid substance, which after some time crystallizes ; it has a 

 very bitter taste. On being boiled with alcohol erythrin is converted partly into this 

 bitter substance and partly into pseuderythrin. Now pseuderythrin, Cog H,3 Og, is 

 the £Ether compound of lecanorin Cjg H3 Og, so that it is probable that erythrin either 

 contains lecanorin, as such, or that it easily gives rise to the formation of that sub- 

 stance ; the bitter substance before mentioned is also decomposed by alkalies into 

 carbonic acid and orcin. According to its constitution it ought also to give off alcohol 

 or aether during this decomposition, but nothing of the kind could be discovered. 



Note on the Solvent Power of Solutions of Acetates. By John Mercer, Jun. 



In the course of some experiments on the crude acetate (pyrolignite) of lime, in 

 which the author had occasion to bring the solution of this substance into contact with 

 sulphate of lead (applied in the dry state), he was surprised to observe the solution 

 experience a considerable increase in density, which proved to be owing to the solu- 

 tion of a large quantity of sulphate of lead. A portion of the liquid gave an abundant 

 precipitate of chrome yellow, with a few drops of a solution of the bichromate of 

 potash ; but the original solution did not contain a trace of lead, nor did the sulphate 

 employed in these experiments contain any soluble salt of lead. 



The solution of the sulphate of lead is not affected by the impurities present in the 

 crude acetate, as pure acetate of lime was found to possess an equal solvent power on 

 the sulphate of lead. 



As might have been expected after such a result, unequivocal evidences were ob- 

 tained of the presence of lead in acetates prepared by double decomposition of the 

 acetate of lead and a soluble sulphate, as acetates of soda, alumina and potash. The 

 acetate of soda of commerce prepared in this manner, contained a notable quantity of 

 lead, evidenced by bichromate of potash, sulphuric acid, and other reagents, though 

 the acetate was in the state of large and perfectly transparent crystals. 



A solution of acetate of soda prepared in the same way by the author, also con- 

 tained lead, although the acetate of lead was not present in excess, for the addition of 

 sulphate of soda to the liquid caused no precipitate. Moreover a solution of pure 

 acetate of soda, prepared by carefully neutralizing acetic acid with caustic soda (both 

 free from lead), was fcfund to be capable of dissolving a large quantity of sulphate of 

 lead, especially with the application of heat. All the acetates the author has had an 

 opportunity of examining, namely, those of lime, soda, alumina, potash, ammonia, 

 and magnesia, possess this solvent power. 



The sulphate of lead is not the only lead compound insoluble in water which is ca- 

 pable of being dissolved by solutions of acetates, for the oxide, carbonate and subsul- 

 phate also partake of the property. The author has not yet been enabled to determine 

 with certainty the exact state in which the lead exists in solution ; the compound 

 formed, however, would seem to be very stable, as the liquid may be boiled, diluted and 

 evaporated until transparent crystals are obtained (where the acetate used is capable 

 of crystallizing) without the separation of the lead. 



It is perhaps worthy of observation, that the solutions of lead in acetates afford a 

 precipitate of sulphate of lead with sulphuric acid, but not with sulphate of soda. 

 Caustic soda also produces a precipitate. 



The solvent power of acetates extends to many bodies insoluble in water besides the 

 lead compounds above mentioned : for instance, a solution of neutral acetate of soda 

 dissolves hydrated oxide of copper and lime in very large proportion ; and alumina, 

 protoxide of iron, and protoxide of tin, in small quantity ; but hitherto the author has 

 not had an opportunity of pursuing the investigation of this subject to the extent it 

 deserves. 



On Guano. By Robert Warington. 

 This was a notice intended particularly to draw attention to the importance of the 

 estimation of the niti'ogen in the analysis of guano as given to the agriculturist, as 

 on the quantity of this element depended, in a great degree, the value of a given 

 sample, whereas in general the per-centage of ammoniacal salts was only given. It 

 appears, from Mr. Warington 's experiments, and the use of guano in the production of 

 the prussiate of potash, that the proportion of this element is very considerable. 



