Polytechnic Association Proceedings, 723 



atmosphere, but that the color has its origin hi the material of 

 which some of the planet's surface is composed. 



IMPROVED INSULATOR. 



A new insulator for telegraphic purposes has been brought out 

 in Philadelphia, which consists in giving the ordinary sulphur and 

 glass insulator a coating of paraffine; this being a thorough repel- 

 lant of water, is found to make the insulator more perfect in wet 

 weather. 



THUNDER MADE VISIBLE. 



Dr. Topler focalizes a ray of light on the object glass of a tele- 

 scope, which is connected with a screen in such a way that any 

 disturbance of the air becomes visible; for instance, the intense 

 sonorous vibrations of the atmosphere produced by electric explo- 

 sions, show themselves in the telescope as visible rings or circles 

 of light. 



METALLIC VEGETATION. 



This new chemical toy is founded on the decomposition of a 

 solution of silicate of soda and a metallic salt, such as crystalized 

 chloride of iron, proto-chloride of cobalt, nitrate of uranium, or 

 sulphate of protoxide of manganese. A tumbler, having a flat 

 bottom, is first filled with silicate of soda of a density equal to 22 "^ 

 Baum6, and then small fragments of a salt are thrown in. After 

 some hours a miniature forest may be seen, variegated by remark- 

 able forms and most brilliant colors. 



THE SLAUGHTER OF CATTLE. 



A series of experiments took place lately in Paris, with a view 

 to try whether oxen might not be spared the frightful tortures it 

 is supposed they endure on being felled with sledge-hammers. 

 Physiologists had aflirmed that the section of the spine will strike 

 the animal down as if by lightning, but the experiments have not 

 corroborated this opinion. Oxen not only showed signs of life, 

 but gave evidence of suffering for more than fifteen minutes after 

 this operation. Experiments were tried on sheep and calves with 

 similar result. 



EXPLOSION EXPERIMENT. 



The Paris Casinos describes an interesting experiment, which 

 may be new to many of our readers. A large bell-glass, full of 

 air, is placed over water, and a stream of mixed air and hydroofen 

 gas is slowly sent up through the Avater, so that each bubble of 



