1865.] Double Chlorides and Oxalates. 147 



double salts, as shown in the foregoing experiments, are, first, the disinte- 

 gration, and at length complete dissolution of a class of salts of very 



Fig. 3. Fig. 4. 



sparing solubility, in strong solutions of chlorides of the same base, whilst 

 weaker solutions do not in the least affect them ; secondly, the combina- 

 tion under these circumstances of the oxalate and chloride of these bases to 

 form double salts almost as little soluble as the simple oxalates ; and lastly, 

 the continued and simultaneous solution and deposition of these salts in a 

 crystalline form in a quantity of fluid but little, if at all, exceeding the 

 weight of the crystals deposited, until either all the oxalate crystals 

 employed at the commencement are used up, or the solution of the chloride 

 has become too feeble to effect the further disintegration of those which are 

 in excess. The most remarkable part of this process is the continued de- 

 position of crystals after the saturation of the fluid in which they were 

 formed, rendering a small portion of fluid sufficient for the production of a 

 comparatively large quantity of crystals. This fact seems to indicate that 

 in this case the newly-formed particles, immediately on their coming into 

 existence in this fluid medium, are attracted more forcibly by the fluid 

 than by one another, but that afterwards, when they have become aug- 

 mented to a point above that which is said to be the point of saturation, 

 their attraction for one another becomes greater than that for the fluid with 

 which they are in contact ; and being thus brought within the sphere of 

 action of the forces necessary to produce crystals, these particles combine 

 into the crystalline form. 



Whether under conditions like the above a deposition of crystals is a 

 necessary attendant on the formation of sparingly soluble substances in a 

 fluid medium, it is not possible to say ; but in course of these investigations 

 I shall be able to adduce several other examples of a similar kind. 



The experiments which have been related so far have gone only to 

 exemplify the influence of quantity of matter on chemical affinity as con- 

 nected with simple chemical combination, but by a slight modification of 



