206 F. W. Clarke—Specific Gravity Determinations, 
These calculated values correspond to a supposed constant 
difference in the molecular volume, of 16°5 for each CH, group; 
a difference which holds in a great many series of compounds, 
This difference may also be made out, within narrow limits of 
approximation, in the series of sulphocarbonates previously 
given. Here, for example, we have, very nearly, 
Methy] salt, molec. vol. 88, calc. sp. gr. 1°658. 
Ethyl “ “ © 104°5, calc. sp. gr. 1°531. 
Isobutyl “ . “137s, “ OED tac Fi 
It will be seen that all these calculated specific gravities 
agree closely with those actually found; and that, curiously 
enough, the molecular volumes thus assumed are exact multi- 
ples by whole numbers of Kopp’s well known value for hydro- 
gen, 55. Are these regularities mere coincidences, or do they 
indicate the existence of some general law 
may give, in conclusion, a few determinations of specific 
gravity made by myself. 
Potassium chloroplatinite, PtCl,.2KCl, 32909, 21°; and 
3°3056, 20°°3. 
Telluric acid, crystallized, H,TeO,.2H,O, 2°9999, 25°°5; 
and 2°9649, 26°5.* 
Fegan acid, H,TeO,, 3-425, 18°°8; 3-458, 19°-1; 3-440, 
2 
Ammonium tellurate, (NH,),TeO,, 3°024, 24°-5 ; 3-012, 25°. 
Thallium tellurate. Forthis compound, hitherto undescribed, 
I can give only a few preliminary facts. By a series of mishaps 
my material became exhausted, so that I was unable to complete 
the investigation of the substances obtained. Metallic thallium 
is not attacked even by a boiling solution of telluric acid. 
hen, however, a solution of ammonium tellurate is added to 
* Oppenheim, Jahresbericht, x, 213, gives 2°340. 
