122 Notice of some Recent [Feb. 



it apparently precipitated, it dissolved again, leaving apo- 

 crenate of copper. 



This is slightly soluble in the filtered liquid, but when 

 washed, it is completely dissolved. These washings were not 

 mixed with the liquid passing through the filter. The latter 

 was saturated with carbonate of ammonia in slight excess. 

 and then was gently heated to 50° C (122° F) when the 

 crenate of copper fell down. As long as the solution con- 

 tinues green, it is a proof that the precipitation is not 

 completely effected, and is to be remedied by the cautious 

 addition of carbonate of ammonia, or by heating the solu- 

 tion. The crenate of copper possesses a light grey-green 

 colour, if brown, it contains apocrenic acid. 



It was then washed, mixed with a little water, and a 

 current of sulphuretted hydrogen passed through it. The 

 sulphuret of copper thus obtained was brown, and the solu- 

 tion which passed through the filter was also brown. 

 After standing 24 hours in a corked flask, it was filtered. 

 The metallic sulphuret was so much the longer in separat- 

 ing from this solution, in proportion to the quantity of 

 water added. It frequently happens, that when the solu- 

 tion passes through at first clear, the metallic sulphuret 

 begins to follow during the process of washing, in conse- 

 quence of the formation of bicrenate of copper. The 

 brown solution was heated in a corked flask at a tempera- 

 ture of 80° C (176° F,) and thrown on a filter. The filtered 

 crenic acid formed a pale yellow solution, which must be 

 kept from the access of the air, for then it is converted 

 into apocrenic acid. By evaporation, free from the contact 

 of air, a dark yellow mass was obtained, consisting of 

 crenic acid, crenates of lime, magnesia and manganese, 

 which was treated with absolute alcohol. Crenic acid and 

 a trace of crenate of magnesia were taken up, while the 

 other bases remained as acid salts. The alcoholic solution 

 was evaporated, free from the contact of air. The residue 

 possessed a yellow brown colour. It was dissolved in 

 water, and mixed with a solution of acetate of lead. The 

 first precipitate formed was brown, which partly dissolved, 

 leaving a brown residue of apocrenate of lead. The so- 

 lution was filtered and precipitated with acetate of lead. 

 The precipitate was well washed, dried, excluded from 



