CHEMICAL SCIENCE. 217 



by its timely application, the bleeding from large and dangerous 

 wounds may be immediately staunched. In addition to the other 

 valuable qualities of this liquid, it is totally devoid of poisonous agency, 

 and easily prepared as follows : Take 8 ounces of gum benzoin, 1 

 pound of alum, and 10 pints of water. Boil all together for the space of 

 eight hours in an earthenware glazed vessel, frequently stirring the mass, 

 and adding water sufficient to make up the original quantity of that 

 lost by ebullition, taking care, however, to add the water so gradually 

 that boiling may not be suspended. The liquid portion of the com- 

 pound is now to be strained off, and preserved in well-corked bottles. 

 It is limpid, like champagne as to color, possessing a slightly styptic 

 taste, and an agreeable odor. 



ALKALIES IN PLANTS. 



AT a recent meeting of the Botanical Society, London, Dr. 

 Daubeny detailed some experiments undertaken by him at the Oxford 

 Botanic Garden, with the view of determining whether the usual 

 quantity of potash and soda existing in barley might be made to vary 

 by causing the plant to grow in soil impregnated with more than the 

 ordinary quantity of one or the other of these alkalies. He found that 

 when the barley had grown in a soil which had been dressed with a 

 strong solution, either of carbonate of soda or of chloride of sodium, the 

 ashes of the plant contained about eight per cent, more soda than was 

 present when the plant had grown in a soil impregnated with carbon- 

 ate of potash, or left unimpregnated. This difference may admit of 

 explanation by supposing one alkali capable of replacing the other 

 within the organism of the plant ; but the author thinks it more 

 probable that it arose from the sap circulating through the plant at the 

 time when it was cut, containing in the one case more soda than it did 

 in the other. The saline contents of the fluid of the sap would of 

 course be confounded with those which had been actually assimilated 

 by the plant, and hence, from the variation in its composition, must 

 tend to modify the amount of the alkalies obtained from the ashes of 

 the plant in each instance, according to the nature of the material with 

 which the soil had been impregnated. 



ON THE EFFICACY OF BURNT CLAY. 



DR. VOELCKER publishes a communication in the Chemical Gazette, 

 for April, on the causes of the agricultural efficacy of burnt clay, in 

 which he shows conclusively, that the change effected, and benefit 

 resulting, is entirely of a chemical nature. 



Prof. Johnson, the well known Agricultural Chemist, had previously 

 expressed the opinion that the mechanical effects of the burning upon 

 clay, were insufficient to explain its efficacy, and first pointed out the 

 true solution of the phenomena in the chemical changes which the soil 

 undergoes. 



Pure clay, silicate of alumina, is rarely found ; such a soil could 

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