RECOMMENDATIONS. 
117 
promoting the following inquiries, with a view to examine the 
theory of Isomorphism, and the connexion between the cry¬ 
stalline forms and chemical constitutions of Minerals :— 
I. To determine whether the angles of varieties of the same 
species (in the usual acceptation of identity of species,) are 
identically the same, under various circumstances of colour, 
appearance, and locality; and if not, what are the differences. 
II. To determine the chemical constitution of such varieties, 
—the specimens, mineralogicallyand chemically examined, being 
in all cases the same. 
III. To determine what quantity of extraneous substances 
may be mixed with a crystalline salt, without altering its form. 
IV. To determine the angles of the various species or varie¬ 
ties of isomorphous or plesiomorphous groups,—and their re¬ 
spective chemical composition. 
That a list be drawn up and printed of substances considered 
isomorphous* and of those considered isomericf. 
List of simple substances and binary compounds presumed to 
replace each other. 
Sulphur .. S 
Selenium................ Se 
Chrome . Cr 
Vanadium?. V 
Soda . N 
• 
Oxide of Silver . Ag 
Sulphuric Acid .......... S 
Selenic Acid . Se 
Chromic Acid .. Cr 
Vanadic Acid ? . V 
• • • 
Manganic Acid .......... Mn 
Potash ... K 
Ammonia+2 atoms water n + 2q 
(2 Ammonia-f 2 water of Ber¬ 
zelius.) 
Phosphorus. P 
Arsenic . .. As 
Antimony .. Sb 
Hyperchloric acid .. Cl 
Hypermanganic acid .. Mn + Mn 
Chlorine ..... Cl 
Fluorine ................ FI 
(2 Cl and 2 FI of Berzelius.) 
Tellurium .. Te 
Phosphoric Acid .. P -f P 
Arsenic Acid ......... As + As 
Antimonic Acid ?. Sb + Sb 
* The lists of isomorphous substances have been drawn up for the Committee 
by Professor Miller. 
f For the list of isomeric substances, see the Report on Chemistry. 
