D. CHEMISTRY AND METALLURGY. 215 



are produced with alcohol or with ether in place of a salt. 

 The most important practical feature of Mr. Guthrie's dis- 

 covery, however, lies in its applicability to the production 

 of constant, low temperatures. As is well known, water, 

 when passing from the solid to the liquid state, remains 

 steadily at Centigrade until the change is complete. Just 

 so each of these cryohydratcs has a constant melting point 

 which can be maintained in any mass of material until the 

 whole is fused. The cryohydrates thus far examined com- 

 mand a range of temperatures from to 28 Centigrade. 

 In order to maintain a vessel at any temperature between 

 these limits, it need merely be surrounded by the proper 

 cryohydrate in a partially melted condition. Then, until 

 either complete fusion or complete solidification of the cryo- 

 hydrate has occurred, the temperature can not vary. 7 A, 

 January, March, and April, 1875, 1, 206, 266. 



DECOLORIZING PROPERTIES OF OZONE. 



M. Boillot ascribes the bleaching effects, heretofore credit- 

 ed to chlorine, as being really due to ozone. Ozone, employ- 

 ed directly, acts as an oxidizing agent, laying hold of the hy- 

 drogen of the substance with which it is in contact, and 

 bleaching it if the body is colored. The action of chlorine 

 the author explains as follows : On allowing chlorine to act 

 upon any animal or vegetable matter, it decomposes a cer- 

 tain quantity of water, and seizes its hydrogen, forming hy- 

 drochloric acid. The oxygen set free by this reaction is 

 transformed into ozone, which in its turn lays hold of the 

 hydrogen of the organic matter. 6 JB, May 3, 1875. 



NEW FACTS CONCERNING OZONE. 



Professor Bottler has succeeded in demonstrating that 

 not only during the decomposition of water, but also on its 

 formation by the union of oxygen and hydrogen, appreciable 

 quantities of ozone are generated. In this connection we re- 

 call the fact announced several years ago by Dr. Pincus that 

 ozone is formed during the burning of hydrogen, and that if 

 a jet of this gas issuing from a fine point is ignited, the smell 

 of ozone can be distinctly recognized. In close connection 

 with both of these observations, however, is the discovery 

 previously made by Mr. Loew, and since patented by him, 



