438 



Dr. J. E. Reynolds on a New Group of [Apr. 20, 



3rd. By the fact that heat alone is able to effect the decomposition of 

 the potassium salt, a solution of the latter giving a yellowish- white precipi- 

 tate of the anhydrous mercuric ketone compound on violent ebullition, 

 the alkali remaining dissolved*. Re-solution does not take place on cool- 

 ing, or on digestion with an excess of the metallic hydrate at the ordinary 

 temperature. 



It is, however, worthy of note here that the gelatinous precipitate produced 

 by acetic acid in a solution of the potassium salt is soluble in excess of 

 potassium hydrate immediately after its formation ; but it soon loses this 

 property and alters somewhat in appearance, becoming more dense. 



With a view to obtain, if possible, some evidence of the basicity of the 

 acid, a quantity of mercuric chloride was dissolved in water, the theore- 

 tical proportion of pure acetone added, and excess of potassium hydrate. 

 Complete re- solution of the mercuric oxide was obtained as usual. To 

 the alkaline liquid dilute hydrochloric acid was added, until a moderate 

 quantity of the white mercuric-acetone compound had been precipitated. 

 The whole was then filtered as clear as possible. The filtrate now contained, 

 in addition to potassium chloride resulting from the reaction, a certain 

 amount of the mercuric-acetone compound, held in solution by a minimum 

 of alkali. In order to determine the ratio between the anhydride or 

 acid and potassium present in combination, 100 cub. centims. of this 

 solution were now taken, treated with excess of hydrochloric acid, and 

 the mercury precipitated as sulphide by means of sulphuretted hydrogen. 

 The pure mercuric sulphide obtained in this manner weighed ]*056 

 gramme: this amount represents 1*1591 gramme of the anhydrous 

 mercuric-acetone compound, as calculated from the formula already found 

 for that body. 



Another 100 cub. centims. of the same solution were taken, and dilute 

 sulphuric acid of known strength very. cautiously added, until a drop of 

 the liquid faintly reddened blue litmus-paper : 5*4 cub. centims. of acid 

 were required; this amount of acid represented '2106 gramme of potas- 

 sium. 



100 cub. centims. of the solution, completely free from excess of alkali, 

 therefore contained of 



grm. 



(CO(CH 3 ) 2 ) 2 Hg 3 3 1-1591 



K' -2106 



These numbers, when divided in the usual way by the respective atomic 

 weights, gave the proportion of 1 : 3*6. 



The foregoing experiment is but one of many performed with a similar 

 result, the main ratio found for different solutions being 1 : 3*7. When 

 the conditions under which the determinations were made are considered, 

 the ratio 1 : 4 may be admitted as the true result. 



* In this, as in many other respects, a strong solution closely resembles in deport- 

 ment a liquid containing white of egg. 



