Intelligence and Miscellaneous Articles. 455 



after this skilful anatomist had announced the discovery of an organ 

 in the rays analogous to that of the torpedo, I tried in vain to obtain 

 signs of electricity in the organ of the ray. In regard to this point, 

 I must own that I was only able to operate upon small and not very 

 lively rays, and that very probably I did not succeed in satisfactorily 

 detecting the organ found by M. Robin. M. Schiff has lately 

 helped me in the preparation, and has taught me to recognize the 

 organ of the ray. Operating upon a very lively and tolerably 

 large ray, and inducing in this fish a number of very strong con- 

 tractions, I obtained with the galvanoscopic frog, the nerve of which 

 was laid upon the organ, evident signs of electric discharges. I 

 wished to vary this experiment and to repeat it upon other 

 rays, but I was unable to procure them. As the electric organ of 

 the ray is enveloped in a large quantity of muscular substance, I 

 would suggest to M. Robin to repeat and vary his beautiful experi- 

 ment by operating upon the isolated organ of the fish, so that no 

 doubt may remain that the electric effects obtained are not attri- 

 butable to the muscular fibre. The difference in the dimensions and 

 the number of the elementary cells, and the nerves, of the electric 

 organ of the ray and that of the other electric fishes, gives great 

 importance to the complete study of this function of the ray ; and 

 this study should explain the peculiar electric phenomena discovered 

 by M. Robin in the electric function of the ray, and which cannot be 

 verified in the other electric fishes. — Comptes Rendus, Oct. 16, 1865. 



ON A NEW AVENTURINE, WITH CHROME AS A BASE. 

 BY M. J. PELOUZE. 



It is well known that the sesquioxide of chrome imparts a green 

 colour to fluxes, and especially to glass. The bichromate of potash 

 possesses the same property, as it is decomposed by heat into oxide 

 of chrome and neutral chromate of potash. The latter salt is in its 

 turn decomposed by the silica, whence result oxygen, silicate of 

 potash, and oxide of chrome. 



Hence, in the presence of silica, all the chromic acid of the alkaline 

 bichromate passes into the state of oxide of chrome, which remains 

 in the glass. If the proportion of the salt is small, the glass is trans- 

 parent, perfectly homogeneous, and of a green colour with a yellowish 

 tinge. But if it is larger in a certain proportion, spangles of the 

 sesquioxide of chrome are found in the glass. 



My experiments were made with the following proportions, which 

 have always been the same, the proportion of the chromate alone 

 being variable : — 



Sand 250 parts, 



Carbonate of soda 100 „ 



Calcareous spar 50 „ 



First Experiment. — With 10 grms. of the bichromate the glass 

 melts, refines, and anneals well. It is homogeneous, transparent, 

 and green with a tinge of yellow. 



-Second Experiment — With 20 grms. of the bichromate the glass is 

 worked and annealed as easily as in the preceding case ; its colour 



