F. W. Clarke—Specific Gravity Determinations. 201 
IX. Some Specific Gravity Determinations. 
The following specific gravity determinations represent work 
done by my students and myself during the school year 1877- 
1878. Those-portions of the work which were entrusted to 
students were carried out under my immediate supervision, and 
every precaution was taken to ensure a fair degree of accuracy. 
The salts were all weighed in benzol, and the figures refer to 
water at its temperature of maximum density as agg 
To Mr. W. H. Creighton and Mr. E, F. Wittmann I assigned 
mercuric cyanide and some of its double compounds. For the 
cyanide itself, HoCy,, we found a sp. gr. of 4:0262 at 12°, 
oo ; 40026 at 22-2, Wittmann; and 4:0036, 14°-2, F. W. 
Clarke.* 
For the oxy-cyanide, HgCy, HgO, Mr. Creighton found 4:437 
at oe and I myself, in two determinations, 4-428 and 4-419 
at 23°-2. 
For the double salt HgOy,HgCl,, Mr. Wittmann obtained 
the values 4531, 21°-7, and 4514, 26°. 
For the double cyanide of mercury and potassium we 
have, from experiments made by Mr. Creighton, 2°4470, 21°2; 
eo 21°5; and 2:4551, 24°. This salt is the well known 
vy. : ‘ 
ercuric eunide, prepared by Mr. Miles Beamer, gave 
57461, 18°, and 5-7298, 16°.+ 
* Bédeker, Jahresbericht 1860, gives for HgCy, the value 3°77, 13°. 
+ Karsten, Schweigg. Journ., v. 65, gives 5-9202. 
