CHEMICAL SCIENCE. 200 



nection with the phenomena, but the boiling of the mercury seemed 

 to have some influence on them. On analyzing the two powders, 

 sulphur was detected. But as a yellow compound of mercury and 

 sulphur contains oxygen, and as no oxygen was found in the black 

 powder, it may be questioned whether the first compound takes oxy- 

 gen from the air of the bulb, and returns it in passing to the state of 

 the black one, or whether some hitherto unknown exchange takes 

 place between the elements of the glass and the mercury. 



ON THE MANUFACTURE OF SODA. 



FROM a lecture read before the Royal College of Chemistry, in London- 

 by Dr. Sheridan Muspratt, on the manufacture of soda, we make the 

 following extracts : 



^3 



" The present method of making soda from common salt (chloride 

 of sodium) was discovered by Leblanc, a Frenchman, near the close 

 of the last century. It was not, however, successfully introduced into 

 England until the year 1820. Before the manufacture of this alka- 

 li, two articles were used in its place, namely, Spanish barilla and 

 kelp. The former contained about 18 per cent, of alkaline principle, 

 and sold for 11 per ton, the latter about five or six per cent., and 

 cost 5 per ton. It is clear that out of 100 parts of these substances 

 95 parts of kelp and 82 parts of barilla were loss, because they were 

 of no service in the manufacture of soap. The introduction, there- 

 fore, of so strong and cheap an alkali as soda would necessarily prove 

 a great boon to the soap-maker ; but at the commencement it was very 

 difficult for the soda-manufacturer to dissipate the prejudices in favor 

 of kelp and barilla. As soon, however, as it was shown that soap 

 could be alkalized for 2 per ton instead of 8, and that the opera- 

 tion was performed in one third of the time, the soda immediately 

 came into general demand, so that in less than twenty years from its 

 first introduction the quantity of soda manufactured exceeded 72,000 

 tons. Of this quantity one manufacturer produced one ninth, and 

 Liverpool exported as much soap as the whole of England had done 

 prior to the introduction of soda. 



" But the change produced by the introduction of the manufacture 

 of soda into England, as regards the traffic and importations of several 

 articles, is still more curious, as shown by the following table: 



Importations. 1824. 1847. Increase. Decrease. 



Pot and pearl ashes, 58,126 barrels. 19,644 barrels. 38,482 



Palm-oil, .... 8,997 casks. 56,891 casks. 47,894 



Sulphur, .... 5,447 tons. 24,220 tons. 18,773 

 Barilla, .... 5,722 tons. 



" The quantity of soda exported from Liverpool alone to the United 

 States, in the year 1847, was upwards of 8,000 tons. 



" On viewing the above statistics, we find that the quantity of alkali 

 shipped from one port is much greater than all the potashes imported 

 into England. The import of sulphur has increased more than four- 

 fold, and palm-oil six-fold, from 1824 to 1847; foreign barilla is en- 

 tirely superseded. Although in this number of years the imports of 



18* 



