418 Prof. KreiPs Deductions from the first Year's Observations 



it to analysis, and found it to be pure sulphuret of cadmium. 

 His analysis was performed on 3*71 grains. 



It is always crystallized in six-sided pyramids. The sum- 

 mit is sometimes replaced by a more acute pyramid : some 

 of the crystals show a six-sided prism. 



Translucent to transparent. 



Lustre vitreous, or sometimes almost adamantine. 



Hardness about 2*75. 



Specific gravity 4*534 ; but the specimen was not quite 

 pure. Mr. Connel states the specific gravity to be 4*842 ; 

 but the determination was made on 3*68 grains. If the im- 

 purity in my specimen was prehnite, the specific gravity of 

 pure sulphuret of cadmium will be 4*546. 



On subjecting it to analysis I obtained 



Sulphur 22-4 or 1*009 atom. 



Cadmium ... 77*6 or 1 atom. 



100*0 

 This very nearly agrees with Mr. Connel's analysis, who 

 obtained from 3*7 1 grains of the mineral, 



Sulphur 22*56 



Cadmium 77*30 99*86 



Professor Jameson has distinguished this mineral by the 

 name of Greenockite, in honour of Lord Greenock, who first 

 discovered it. 



LXI. Deductions from the first Year's Observations at the 

 Magnetic Observatory at Prague: in a Letter from Pro- 

 fessor Kreil, Director of the Prague Observatory, to Major 

 Edward Sabine, R.A., V.P.R.S* 



Prague, July 21, 184th 



I HAVE seen with great pleasure, by your last letter and its 

 inclosure, that you have made known in Englishf, my let- 

 ter to M. Kupffer, containing the results of the Milan Mag- 

 netic Observations, and that you have sent it to the newly- 

 established Observatories, I am indeed far from regarding 

 all the deductions from those observations as undoubted facts ; 

 I consider them rather as indications afforded by the first made 

 continuous series of observations, and awaiting confirmation 

 or correction from subsequent researches. 



Since my arrival at Prague, I have had the advantage of 

 several zealous assistants, and have been able to make the ob- 

 servations with the magnetic instruments at much shorter in- 



* A translation communicated by Major Sabine, 

 f See Lond. and Edinb. Phil. Mag., vol. xvi. p. 241. 



