538 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



turned rubies violet. Rose quartz and amethyst were decolorized, but re- 

 mained transparent. Turquoise was blackened, as were marbles, agates 

 and granites, colored with the oxide of iron. 



The Chairman added, as the chemical constituents of the minerals exneri- 

 mented upon may not be remembered by all present, it may be interesting 

 to briefly state tliem. 



Marbles are limestone, more or less pure, that is carbonate of lime, con- 

 sisting of one equivalent of calcium, one of carbon, and three of oxygen; 

 or, in other words, of lime and carbonic acid. 



Verde Antique, a clouded green marble, consists of a mixture of lime- 

 stone and serpentine; the latter is composed of nearly equal parts of silica 

 and magnesia, with water and a trace of the oxyd of iron. 



Quartz is pure silica, according to Berzelius, Si O2, but the later chemists 

 regard it as consisting of Si O3. 



Amethyst, Carnelian, (commonly called Cornelian,) agate, jasper and 

 opal, are varieties of quartz. 



Diamond is pare carbon in an allotropic state diflering from charcoal, 

 mineral coal and plumbago. 



Sapphire is pure alumina, AI2 O3. Some varieties of these crystals rank 

 in value next to the diamond. Dingy clouded crystals of pure alumina, 

 are called corundum. Emery is a granulated bluish gray or black variety. 



Topaz is composed of alumina, silica, and fluorine. Emerald is a variety 

 of beryl which consists chiefly of silica, alumina and glucina. Emerald 

 owes its rich green color to the presence of about one per cent of the oxyd 

 of chromium. 



Ruby is a variety of spinel, essentially alumina and magnesia. Garnet 

 is a combination of silicates of alumina, lime, iron and manganese. 



Turquoise is composed of alumina, phosphoric acid and water, with a 

 small quantity of the oxyd of copper and iron. 



Granite is composed of feldspar, quartz and mica, and generally contains 

 about seventy-two per cent of silica, fifteen of alumina, seven of alkalies, 

 and five of lime, magnesia and oxyd of iron. 



Anaesthetic Agents. 



Mr. T. D. Stetson — In regard to the annesthetic agent alluded to by the 

 chairman, I wish to enquire whether it is safe, or if the nitrous oxide now 

 given principally by dentists is to be preferred. 



The Chairman — All antesthetic agents might be regarded as dangerous, 

 unless administered with great caution. The reason of this will be per- 

 ceived if we look at the formula of the several compounds alluded to; chloro- 

 form being C2 H CI3 ; Ether C4 Hs 0; Nitrous Oxide N 0; the latter con- 

 tains only the principal elements of common air. Amylene, Cio Hio, has 

 been employed in surgical operations, but frequently with fatal results. 

 Its use is abandoned. The nitrate of Amyl, Cio Hii N Oe , found by Dr. 

 Richardson to suspend the action of the heart, cannot be taken with safety. 



Common air is a mechanical mixture of four volumes of nitrogen, one 

 of oxj'gen, with a little carbonic acid, water, and a trace of ammonia, 

 Nitrous oxide is vastly more energetic than air, because the relative 

 amount of oxygen is doubled. Nitrous oxide was the first anaesthetic 



