Chemistry and Physics. 473 



readily scratched red, blue, white, pink, and yellow corundum 

 in the form of fine gems. It having been suggested that this 

 material would cut and polish a diamond, an experiment was 

 made on a new wheel. After several trials had been made, it 

 was found that carborundum would not scratch or polish the 

 diamond, but on the other hand it was easily scratched by 

 diamond cleavages, and crystal faces. This experiment is only 

 mentioned as it precludes any possibility of the material which 

 has been found in the Canon Diablo meteorite being any such 

 compound of carbon and silicon, such as the new and interest- 

 ing abrasive material just mentioned. But it establishes the 

 fact that we have an artificial substance that exceeds all natu- 

 ral substances except the diamond in hardness, i. e. being 

 harder than 9 — but still far distant from 10. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistky and Physics. 



1. On the Mass-composition of Water. — The mass-composition 

 of water has been determined with great care by Dittmar and 

 Henderson, the synthesis being accomplished by the action of 

 hydrogen on copper oxide. A specially devised apparatus was 

 employed for the purpose consisting of the reduction tube, with 

 the necessary purifying and drying train before it and the water 

 receptacle and drying tubes after it. About 115 grams copper 

 oxide was placed in the reduction tube, and this was heated on a 

 magnesia bath in a current of dry air. The next day the tube 

 was exhausted, filled with hydrogen, allowed to assume the 

 temperature of the balance case, again exhausted noting the 

 pressure, and weighed. The apparatus was thus connected to- 

 gether, several liters of hydrogen were passed through it to free it 

 of air, and the reduction tube was heated. The reduction of the 

 copper oxide takes place below redness, the water receptacle 

 being cooled first by ice and then by water. After the reduction 

 is complete, the apparatus is allowed to cool, the hydrogen con- 

 tained in it is replaced by dry air, and its various parts are dis- 

 connected and weighed. The loss of weight of the tube gives 

 the mass of oxygen employed and the increase of weight of the 

 water flask and its drying tubes, the mass of water produced. 

 The values obtained were carefully corrected. The first series of 

 experiments was made to test the apparatus and to acquire famil- 

 iarity with it. The results of the second series show that as a 

 mean of the experiments 8 grams of oxygen required 1*00879 

 grams of hydrogen to form water; the result of the seven best 

 experiments being 1*00848 grams. Hence they adopt as the 



