PROCEEDINGS OF TBE POLYTECHNIC ASSOCIATION. ' 553 



per minute, or five times more rapidly than carbonic acid ascended. It is 

 certainly remarkable, he concludes, that in perfeetly still air carbonic acid 

 molecules should spontaneously alter their positions and move a distance 

 of half a metre, in any direction, in the course of five or six minutes. The 

 molecules of hydrogen can disperse themselves to the distance of a third 

 of a metre in a single minute. Such a molecular movement may become 

 the agency of considerable power in distributing heat through a volume of 

 gas. It appears to account for the highly convective power observed in 

 hydrogen, the most diffusive of gases. 



The New Chlorides. 



Mr. Bottger has examined a r.ubstance found in the mother liquors from 

 the Nauheim salt works, used considerably by confectioners as a freezing 

 mixture. He has obtained from it, in addition to the chlorides of potassi- 

 nm, sodium and magnesium, the chlorides of ccesium and rubidinum, with 

 traces of chloride of thallium, from which fact and other properties, altho' 

 it is precipitated by sulphuretted hydrogen, he concludes that thallium 

 should be ranked with the alkalies. 



Coal in Great Britain. 



The available supply of coal in Great Britain, is estimated by Professor 

 Ansted, at 35,000 millions of tons; and he agrees with Sir W. Armstrong, 

 that with the present system of mining and the increased rate of consump- 

 tion, now exceeding 100 millions of tons per annum, two or three centuries 

 will exhaust England as a coal producing country. This is a startling 

 statement to those who comprehend the fact that the real power of Great 

 Britain is derived from her coal fields. - 



Importation of Soda Compounds. 



From the 1st of January, 1862, to the 30th of June, 1863, the soda im- 

 ports into the port of New York alone, are as follows: 

 ^Soda ash, 26,848 tons; bi-carbonateof soda, 13,368 tons; sal soda, 1,997 

 tons; bleaching powders, 7,160 tons; caustic soda, 2,858 tons. In this 

 estimate the ton is rated at 2,000 lbs. The total value of these compounds 

 at the present wholesale prices, is, in round numbers, $5,500,000, 



In relation to this item, the chairman stated that he had received the 

 information directly from the custom house. He wished to direct attention 

 to the importance of manufacturing the articles enumerated in this country. 

 Coal, common salt, and limestone, are the chief raw materials required to 

 make the finished products. These materials can be had as cheap here as 

 elsewhere, and he could see no reason why, with the protective duty now 

 imposed on the imported article, there would be any risk in attempting to 

 compete with foreign manufacturers. In mechanical branches, our people 

 evince great ingenuity, and by labor saving inventions manage to manu- 

 facture as cheaply as others do in the old world where the laborer is poorly 

 paid; but in chemical manufactures we have not shown the same compari- 

 tive ndvance. The field is large, but the workers are few. Those tvho 

 enter it now will find but little home competition, and hence tliere is a fair 

 prospect of their reaping a golden harvest. 



