400 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 







that tliey apply equally well at the ordinary atmospheric 

 temperatures. 



The so-called weathering of coal he ascribes to the absorp- 

 tion of oxygen, which in one case oxidizes a portion of the 

 carbon and hydrogen of the coal, converting it into carbonic 

 acid and water; in the other, entering directly into the com- 

 position of the coal. If, then, the coal becomes heated in any 

 way, a more or less energetic chemical action, varying in pro- 

 portion to the elevation of the temperature, takes place upon 

 the combustible substance of the coal ; but, on the other hand, 

 the process of oxidation proceeds so slowly that the changes 

 occurring within the period of a year can scarcely be estab- 

 lished with certainty, either technically or analytically. 



Moisture, as such, seems to have no accelerating influence 

 upon the weathering of coal, the positive effect being gener- 

 ally appreciable in coal containing a large amount of sul- 

 phuret of iron or pyrites, the decomposition of which is ac- 

 celerated by the water. 



Another proposition of our author is, that pure coal, heaped 

 up for nine months or a year, unprotected from the weather 

 and not allowed to become heated, is changed no more than 

 it would have been in a perfectly dry locality. As long as 

 any increase of temperature does not exceed certain bounds, 

 as from 340 to 375 Fahr., there is no appreciable loss of 

 weight by the weathering ; and, in fact, there should be a 

 slight increase, in consequence of the absorption of oxygen. 

 The decrease in value for combustible purposes, and for other 

 technical applications, which coal experiences by the weath- 

 ering, is produced by a slight decrease of carbon and hydro- 

 gen, and an absolute increase of oxygen in consequence of the 

 exposure. 3 B, Jane 9, 1870, 248. 



CUEING DAMPNESS IN WALLS. 



A Russian preparation for curing moisture in the walls of 

 houses consists in the use of a mixture made by adding two 

 pounds of white resin to a boiling solution of three and three 

 fourths pounds of green vitriol in one hundred pounds of wa- 

 ter. To this, ten pounds of sifted red ochre (or other color), 

 eight pounds of rye meal, and six and a half pounds of linseed 

 oil are to be adcled, and the whole stirred together until it 

 forms a completely homogeneous mass. Two coats of this 



