41.2 



On a New Group of Mercurial Colloids fyc. [Apr. 20, 



tvveen the members of the groups of ketones and of aldehydes suggested 

 the attempt to combine the latter bodies with mercuric oxide. Though the 

 experiments in this direction cannot properly be detailed in this communi- 

 cation, I may be permitted to state that when the aldehyde of the ethyl 

 series was warmed with freshly precipitated mercuric oxide in presence of 

 potassium hydrate, solution of the oxide did not take place, but the latter 

 gradually united with the aldehyde to form a white non-crystalline com- 

 pound. I have not obtained any colloid liquid in the course of my experi- 

 ments with this body. 



Certain other aldehydes of the same series were found to unite with 

 mercuric oxide, yielding soluble compounds easily decomposed by weak 

 acids. 



The investigation of the bodies produced in these reactions has been 

 attended with peculiar difficulty, owing, on the one hand, to the facility 

 with which several aldehydes are converted into resinoid products of va- 

 riable composition by contact with caustic alkali ; and, on the other, to 

 the circumstance that an aldehyde can react either as the oxide of a di- 

 valent group (C n H2n"0), or as the hydride of a monovalent acid radical 

 (C n H2«-iO, H, or, for terms of the series above methylic aldehyde, we 

 may write the formula CO(C?- t H2«-i) H). It may be added, that the well- 

 known tendency of the aldehyde to yield polymeric compounds has in no 

 degree lessened the uncertainty attending the examination of the products 

 of the action of mercuric oxide and alkali upon the members of the group. 



Leaving the statements contained in the last section out of consideration 

 for obvious reasons, I may now be allowed to summarize the results of the 

 investigation detailed in the foregoing pages. It has been shown : — 



1st. That certain fatty ketones can be made to unite directly with mer- 

 curic oxide. 



. 2nd. That the resulting compounds afford a new group of colloid hy- 

 drates, analogous in properties to the silicic, albuminic, and other hydrates 

 already made known by the researches of Professor Graham. 



3rd. That the new hydrates may best be regarded as extremely feeble 

 conjugate acids, the chief member of the group (that derivable from 

 acetone) being probably tetrabasic and capable of affording very unstable 

 salts. 



4th. That the generating reaction for the di-keto-mercurates may, when 

 carefully controlled, be employed as a test for the presence of a ketone 

 (especially for acetone) in certain organic mixtures. 



