225 



mixed with it. It is very difficult to determine wlien this 

 substance can be considered anhydrous. Prepared by eva- 

 poration over sulphuric acid in vacuo, it is quite dry, and 

 may be powdered, but if heated it liquefies below 212°, and 

 continues giving out watery vapour until the temperature is 

 raised to 350°, beyond which the organic matter itself cannot 

 be heated without decomposition. On cooling it reassumes 

 its perfectly dry aspect, and may be easily powdered. 



It was hence analyzed in all these stages of desiccation, 

 with the following results. It contained : 



By adding a solution of xanthorhamnine to solutions of 



acetate of lead, two combinations may be formed, one by 



neutral acetate of lead, the other by using the tribasic salt. 



But it is difficult to obtain either unmixed with some traces 



of the other, and thence the analysis of both vary a little 



from the true atomic constitution. Thus the tribasic salt 



gives 



^ t2 



