1871.] 



Mercurial Colloids and certain Fatty Ketones. 



435 



III. '4940 grm. of another preparation gave '4485 grm. of Hg S. 



IV. -6640 grm. afforded -2344 grm. of C0 2 and -0870 grm. of H 2 O. 



V. 1*2148 grm. of residue of evaporation of colloid liquid gave 9*562 



grm. of Hg. 



VI. *8156 grm. of another preparation gave *6425 grm. of Hg. 



Experiment. 



Calculated. , *■ ^ 



, • N I. II. III. IT. V. VI. 



Carbon 72 9-43 ... 973 ... 9-62 



Hydrogen 12 1-57 ... 1'49 ... 145 



Mercury... 600 78-53 78*10 ... 78-26 ... 7871 78*77 



Oxygen 80 1047 ... 



764 100-00 



The composition of the body is therefore well represented by the 

 formula 



((CH,) 2 CO) 2 Hg 3 Cv 



c. Properties of the Colloid Body, Hydrated and Anhydrous. — Ana- 

 logy would lead us to conclude that the colloidal liquid obtained by 

 dialysis is a hydrate of the body represented by the above formula ; but 

 since evaporation in vacuo is sufficient to remove the water completely, 

 the hydrate can possess but little stability. Properly speaking, this hydrate 

 is no doubt a true liquid, and as such is miscible with other liquids. 



The reaction of this hydrate is neutral to test-papers. 



When the aceto-mercuric hydrate contains five per cent, of the anhy- 

 drous compound, it will, if quite pure, remain liquid for twelve or fourteen 

 days, toward the end of this time becoming gradually less fluid, until the 

 whole " sets" to a firm jelly. The same result may be brought about 

 in a few seconds by the addition to the perfectly neutral liquid of very 

 minute quantities of any of the following substances : — Hydrochloric, 

 acetic, nitric, sulphuric (incompletely), chromic, oxalic, tartaric, or citric 

 acids ; by potassium, sodium, ammonium, barium, and calcium hydrates ; 

 by calcium chloride, mercuric chloride, sodium acetate, and other neutral 

 salts. Contact with certain insoluble powders, such as calcium carbo- 

 nate, and even alumina, induces pectization*. 



Elevation of temperature quickly determines the gelatination of the 

 liquid. If containing five per cent, of the ketone compound, a very firm 

 jelly is produced on heating to 50° C. In one experiment, a quantity of 

 the liquid was taken and some bright, carefully cleaned copper-gauze 

 introduced. The liquid did not pectize, nor did any trace of mercury 

 deposit on the copper, after standing for a day. The temperature of the 

 whole was then raised to 50° C. ; a transparent jelly was at once 

 produced, of such strength that the vessel in which it was contained could 



* In accordance with the nomenclature of Prof. Graham, we must call the liquid 

 colloid hydrate the "hydrosol" of the new compound, the gelatinous hydrate the 

 "hydrogel," and the change from the former to the latter "pectization." 



