176. ~——~Prof. Horsford on the Relations of 
ee 
- 
Art. XX.—Connection between the Atomic weights and the 
physical and chemical propertics of Barium, Strontium, Cal- 
cium and Magnesium, and some of their Compounds; by 
E. N. Horsrorp, Rumford Professor in the University at 
Cambridge. 
Read before the Cambridge Scientific Association.* 
Tue great discovery of isomorphism by Mitscherlich,t and the 
affiliated one by Kopp,t of the identity of the specific volumes of 
isomorphous bodies are among the brilliant points in the progress 
of the chemistry of this century. 
The latter seems to have had its origin in a conviction that in — 
the atomic weight of a body—all its attributes have what may be 
denominated a product expression. 'The factors are form, volume 
and density. ach may vary, and with it the atomic weight 
will vary; for example:—the volume and form being constant, 
increase of density will be accompanied*by increase of atomic 
weight: or form being constant, increase of density will be accom- 
panied by increase of atomic weight, or, density and volume being 
constant, modification of form will influence the atomic weight. 
ties of the metals, barium, strontium, calcium and magnesium, 
the fourth.§ 
The signification of the term intensity, as used above, may be 
thus illustrated. Sulphate of baryta requires 43000 parts of water 
or its solution. Sulphate of strontia 15029 parts at 11° C.|| 
Sulphate of lime (CaO, SO,, 2HO) in 380 parts of cold water, 
and 388 parts of hot water,{I and sulphate of magnesia with seven 
atoms of water, 0:799 parts at 18-75°.** 
Solubility. At. W. 
MsO,80,-.. 4. ... sB00000 1165 
nn A 58, 8 15029-00 91-7 
a0; 805°. ; : 460-00 68° 
Me, SO.) 4 P 0-79 60-7 
* A summary of some of the conclusions arrived at by the author were commu- 
nicated to the American Association of Geologists and Naturalists, at their meeting 
in Boston in 1849. 3s 
+ Ann. Chim. Phys., xiv, 172; xix, 350; xxiv, 264, 265. Pogg. Ann. xil, 137; 
xxv, 300; xlix, 401. 
é Pogg. Ann., xlvii, 132; lii, 248-262. Ann. Chem. u. Phar., xxxvi, 1. ds 
is to be regretted that so little is known of the properties of the compouncs 
of magnesia, Their eminent solubility in water, and the difficulty with which an 
of the salts of this base may be made to crystallize, haye made this field of invest 
gation less inviting than many others. 
| des u. Silber, Br. Arch., iii 
Accordi 
xxxill, 61. 
a Giese. ig to Bucholz, 480 parts cold or hot. 
* Gay Lussac, _ The anhydrous sulphate is soluble at 0° C, in 3°885 parts of water. 
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