434 



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



after the results of the analyses of the anhydrous mercuric compound se- 

 parable from it in the pure condition shall have been stated. 



b. Analyses of the Anhydrous Compound. — I took a considerable volume 

 of the very carefully prepared colloid liquid and divided it in two parts. 

 One portion was very cautiously evaporated to dryness, and the resinoid 

 residue very finely powdered and carefully dried. The second portion was 

 precipitated by the addition of dilute acetic acid, and the gelatinous pre- 

 cipitate washed rapidly and completely with the aid of Bunsen's filter- 

 pump, and the residue dried. The desiccation in each case was effected at 

 first in vacuo over sulphuric acid, and finally on the water-bath. The 

 compound easily bears a temperature of 100° C. - 



On analyzing both products, I found that they were practically identical 

 in composition. The residue of the evaporation of the colloid liquid con- 

 tained, as might be anticipated, a slightly greater proportion of mercury 

 than the precipitate by dilute acid. The circumstances under which the 

 precipitate was produced, however, were such as to give most confidence in 

 the purity of the product ; I have therefore employed this latter or 

 similar preparations in many of the determinations, the results of which 

 will be presently stated. 



The compound was found to contain carbon, hydrogen, mercury, and 

 oxygen, and to be free from chlorine. As the presence of the volatile 

 metal introduced some difficulty in the determinations, it is necessary to 

 describe the plan of analysis adopted. 



The mercury was in some cases obtained in the metallic state by dis- 

 tillation with quicklime ; but I much prefer to digest a weighed quantity 

 of the compound in a sealed tube with dilute hydrochloric acid, and, after 

 complete solution has taken place, to break the tube, precipitate the metal 

 from the contents by sulphuretted hydrogen, and weigh the mercury in 

 the usual way as sulphide. The results are very satisfactory. 



The presence of a large proportion of mercury in the compound 

 rendered the accurate determination of carbon and hydrogen somewhat 

 difficult. At the outset of this investigation I arranged a very troublesome 

 process of analysis, similar to that employed by Messrs. Frankland and 

 Duppa in their analysis of mercuric ethide and its analogues. In all later 

 combustions I have adopted the very simple and satisfactory plan of 

 placing in the anterior part of the combustion-tube a layer of fifteen cen- 

 timetres of any metal capable of easily amalgamating with mercury. 

 Gold- and silver-foil answer the purpose well : no doubt tin-foil might be 

 used in the same way. It is scarcely necessary to add that the tempera- 

 ture of the anterior part of the combustion-tube containing the gold or 

 silver was in each instance very carefully regulated. 

 The following results were obtained : — 

 I. '997 grm. of substance gave '9037 grm. of Hg S. 



II. *8618 grm. of substance gave -3077 grm. of C0 2 and -11 58 grm. of 

 H 2 0. 



