CHEMICAL SCIEXCE. 251 



ammonia, and of the acid of the nitrates as manures ; for we find in 

 rain-water a constant supply of these nitrogeneous matters, not applied 

 once, or at most twice, in the year, as is the case with the various 

 artificial manures, such as the nitrates of potash and of soda, Peruvian, 

 and those guanos which contain a large proportion of soluble ammo- 

 niacal salts, and the various ammoniacal composts, made and sold in this 

 country, the utility of which must chiefly depend on the concurrence 

 of several favorable conditions of the plants, the soil and the weather ; 

 for we find that the nitrogen required for the growth of the plant is 

 supplied in the fittest state lor assimilation (viz., that of great dilution,) 

 and at all stages of its growth, by every shower that falfs. The later 

 opinions entertained by Liebig,* of the superior value of the alkaline 

 and earthy constituents of manures, i. e., the potash, soda, lime, 

 magnesia, and the phosphates and sulphates of these bases, to that of 

 their nitrogeneous compounds, derive much weight from these experi- 

 ments of M. Barral, which show that a vast amount of nitrogeneous 

 fertilizing matter is distributed by the rain but none of the fixed 

 alkalies, or of the salts of phosphoric and other acids, equally important 

 to the due growth of vegetables, and which, unless naturally existing 

 in sufficient amount in the soil, must be supplied by the application of 

 manure, or the plant will either dwindle, or yield an imperfect produce, 

 owing to an insufficient supply to one portion of its requsite constit- 

 uents, however much it may be stimulated by an abundant applica- 

 tion of ammoniacal fertilizers. The prevailing use of these manures, 

 which are so highly charged with the salts of ammonia, readily account 

 for the increasing " steeliness" which is observable in English wheat, 

 arising in great measure, as remarked by Liebig, from a superfluous and 

 unnecessary supply of the ammoniacal stimulants, and a deficiency in 

 the more important constituents of the cereals, -viz. the earthy phos- 

 phates and alkaline salts, which are not brought to the growing corn 

 in the rain, like the nitrogeneous constituents. London Critic. 



ON THE SEPARATION OF BUTTER FROM CREAM BY CATALYSIS. 



AT the American Association, Albany, President Hitchcock read 

 the fallowing paper, on the separation of butter from cream by 

 catalysis : 



It is well known that the separation of butter from cream, during 

 the winter months, by the ordinary process of churning, is often very 

 difficult, from some chemical changes in the proximate principles. 

 From my own small kitchen dairy, the complaint on this subject had 

 so often reached me, that I was led a few years since to inquire 

 whether there were not some remedy. My thoughts were turned to 

 that principle in chemistry, to which Berzelius gave the name of 

 catalysis. In observing the process of churning with the old-fashioned 

 cylindrical churn, I had noticed that along the handle, when the 

 cream had been subject to a more powerful agitation, butter would 

 show itself much earlier than in the body of the churn. Hence I 

 inferred that by acting on a small quantity of the cream, the separation 

 22* 



