566 Chronicles of Science. [Oct., 



the gas on, it escapes readily through the small openings in the 

 canvas, and the gas may be ignited above. The canvas, however, 

 soon takes fire and bums off, but leaves a very complete circular 

 disc, "which remains white and unconsumed in the centre of the 

 flame. If it is desired to demonstrate more completely the nature 

 of the flame, it is done by placing on the middle of the canvas disc 

 some gunpowder, and on it the heads of some lucifer matches. 

 After having again turned on the gas, and left it to escape for a 

 few momente, it may be kindled again, and will burn quietly ; and 

 even though, as in the first experiment, the excess of canvas again 

 bums off, neither the gunpowder nor matches will catch fire until 

 just at the moment the gas is gently turned off. 



M. W. Stein states that the vapour of perfectly pure disulphide 

 of carbon is not decomposed when passed through a red-hot por- 

 celain tube ; but on repeating the experiment and increasing the 

 heat by the application of a strong coke and charcoal fire, the inner 

 space of the tube having been filled with broken porcelain, it was 

 found to be lined with a deposit of carbon, owing to the decompo- 

 sition of the sulphide, while sulphur was collected in a receiver. 



"While engaged with experiments on the intrinsic composition 

 and constitution of various pieces of silver money, made at the 

 Eoyal Netherlands Mint at Utrecht, Dr. A. von Eiemsdyk carried 

 on some experiments on the fusibility and volatihty of metals. The 

 author found that there does not exist any relation at all between 

 the fusibihty and volatility of metals, which may be arranged in 

 the following manner, beginning from the most fusible and most 

 readily volatile : — 



Fusibility. Volatility. 



Tin 228°-5C Cadmium. 



Bismuth .. .. 268° -3 



Cadmium .. .. 320° -0 



Lead 326°-0 



Zinc 420°-0 



Zinc. 

 Bismuth. 

 Lead. 

 Tin. 



Silver melts at 1040° C, pure gold at 1240° C, while the 

 author found that chemically-pure copper requires a temperature 

 of 1330° C. to become liquid. Neither pure silver nor pure copper 

 loses anything at all by volatilization when kept for a considerable 

 time at temperatures higher than the melting-points of both these 

 metals, and in a feeble current of pure hydrogen to prevent their 

 oxidation. The author has made some of these experiments on a 

 very large scale, having at his disposal several hundred kilos, of 

 these metals in pure and alloyed state. 



Electricity. — It may be of some interest to our readers to 

 know the theory which has been formed by the Eev. Father Secchi, 

 S.J., on electricity. He writes, in a letter to M. F. Mazco, at Turin, 



