Chemistry and Physics. 



271 



made on the discharge of the torpedo, and on the analogy between this 

 discharge and muscular contraction, have led me to establish the existence 

 of an electrical discharge in the act of muscular contraction. The gen- 

 eral conclusion to be drawn from these researches is, therefore, that the 

 chemical action which accompanies muscular contraction develops in liv- 

 ing bodies, as in the pile or in a steam-engine, heat, electricity, and vis 

 viva, according to the same mechanical laws. 



Allow me to describe to you briefly the only one of these experiments 

 which can be repeated in a lecture, and which proves the principal fact of 

 these researches, although it is limited to prove that muscles in contrac- 

 tion develop a greater quantity of carbonic acid than those in repose. 

 Take two wide-mouthed glass phials of equal size, 100 or 120 cub. cen- 

 tims. ; pour 10 cub. centims. of lime-water (eau de chaux) into each of 

 these phials. Prepare ten frogs in the manner of Galvani, that is, redu- 

 cing them to a piece of spinal marrow, thighs and legs without the claws, 

 which are cut in order to avoid contact with the liquid in the phials. 

 The cork of one of these phials is provided with five hooks, either of cop- 

 per or iron, on which five of the prepared frogs are fixed. Through the 

 cork of the other phial are passed two iron wires, bent horizontally in the 

 interior of the phial ; the other five frogs are fixed by the spinal marrow 

 to these wires. This preparation must be accomplished as rapidly as pos- 

 sible, and both the phials be ready at the same instant, and great care 

 taken to avoid the contact of the frogs with the sides of the phials or the 

 liquid. When all is in readiness, with a pile of two or three elements of 

 Grove, and with an electro-magnetic machine such as is employed for 

 medical purposes, the five frogs suspended on the two iron wires are made 

 to contract. After the lapse of five or six minutes, during which time the 

 passage of the current has been interrupted at intervals in order to keep 

 up the force of the contractions, agitate gently the liquid, withdraw the 

 frogs, close rapidly the phials, and agitate the liquid again. You will 

 then see that the lime-water contained in the phial in which the frogs 

 were contracted is much whiter and more turbid than the same liquid 

 contained in the other phial in which the frogs were left in repose. It is 

 almost superfluous to add, that I made the complete analysis of the air in 

 contact with the frogs according to the methods generally employed. 



2. Selenium. — Crystalline form according to Mitscherlich (J. f. pr. 

 Chem. lxvi, 257) is monoclinic. 7: 7=64° 56', i2 : i2 (planes beveling 

 front edge) = 103° 40', C (or 0:n) = lO4° 6', O : £i (clinodoine) = 142° 

 54', 0: 1 = 124° 48', 0 : -1 = 1 12° 36'. 



3. Iodine. — Crystalline form (Mitscherlich, J. f. pr. Chem. lxvi, 265) 

 trimetric; 7:7=112° 48', 0:1 = 112° 4', O : li = 126° 13-J-', 0:11 = 

 115° 57', li: li (top) = 72° 27', li : li (top) = 51° 54'. 



II. MINERALOGY AND GEOLOGY. 



1. Meteoric Iron of Thuringia. — Description and analysis by W. Eber- 

 hard, (Ann. Ch. u. Pharm., xcvi, 286.) — Found on the 18th of October, 

 1854, near Tabarz, near the foot of the Inselbergs, not far from Gotha, 

 and said to be still hot when picked up, though this is doubted. The 

 mass is a small one, and is oxydized over the surface. It resembles much 



