1871.] Mercurial Colloids and certain Fatty Ketones, 439 



A solution of the barium salt was now prepared with great care, the 

 presence of excess of barium hydrate being guarded against by very cau- 

 tious manipulation in the first instance, and subsequent treatment with 

 acetone and mercuric chloride, until the liquid ceased to dissolve more 

 mercuric oxide. The acid treatment resorted to in the case of the potassium 

 salt was found to be unsuitable in the present instance : 100 cub. centims. 

 of the clear filtered liquid were taken, immediately after preparation of the 

 solution, and treated with excess of hydrochloric acid until complete de- 

 composition was effected ; the mercury was then precipitated as sulphide : 

 •5062 gramme was obtained; this amount represents *5555 gramme of 

 the anhydrous mercuric-acetone compound. 



100 cub. centims. were treated with a standard acid : 33 cub. centims. 

 were required before an acid reaction was developed; this corresponds 

 to -2244 gramme of barium. 



We therefore find in 100 cub. centims. of the solution of 



grm. 



(CO(CH 3 ) 2 ) 2 Hg 3 3 -5555 



Ba" -2244 



When these numbers are treated as before, we find that the ratio of 

 anhydrous ketone compound to barium is 1 : 1*84. As in the case of the 

 potassium salt, the chances of error are altogether in the direction of 

 under-estimating the barium and over-estimating the remaining consti- 

 tuent of the salt ; the ratio 1 : 2 may therefore fairly be taken as the 

 practical result of these determinations. 



Potassium being monovalent and barium divalent, it would appear that 

 the solutions above mentioned contained respectively the normal potas- 

 sium and barium salts of an extremely feeble but yet distinctly marked 

 tetrabasic acid. When any one of these liquids was evaporated to dryness in 

 vacuo over sulphuric acid, a resinoid mass was in each case obtained, 

 from which metallic chloride was removable by water ; but since partial 

 decomposition appeared to take place daring the process of evaporation 

 in each case, the now insoluble resinoid body, containing potassium, so- 

 dium, or barium, could not be regarded as a pure salt ; nor have I suc- 

 ceeded in obtaining any other solid compound of this acid in a condition 

 Suitable for analysis. 



When to a liquid containing the potassium salt of the acid a solution 

 of potassium hydrate, saturated with zinc hydrate, was added, a semi- 

 transparent gelatinous precipitate was obtained. On washing with water 

 this substance quickly became basic. Other attempts with various metals 

 did not afford better results, precipitates of variable composition being 

 ohtained in each case. It would appear, then, that only the most powerful 

 soluble metallic hydrates are capable of forcing the new acid to remain 

 in combination, and that even these alkaline salts are so feebly held 

 together, that decomposition attends the attempt to obtain them in the 

 solid state. 



vol xix. 2 M 



