318 Extracts from the Journals. [Oct., 



The effects of the compounds of the simple earths are, however, 

 stiil more remarkable, since they surpass greatly that of their in- 

 gredients, and clearly demonstrate that the affections of these 

 bodies for moisture depend less on their peculiar nature than on 

 their mechanical condition. Thus sea-sand gives 70 deg., whin- 

 stone 80, though it consists one-half of silex, and the other of 

 alumine and oxide of iron, in nearly equal parts. 



Whatever tends to harden them diminishes their effect, and the 

 contrary. Thus quartz urged in a forge gives only 19 deg., but 

 the same powder, after being soaked a week In water, gave 35 

 deg. The process, says Mr. Leslie, by which nature gradually 

 softens, divides, and disposes stony bodies to absorb moisture, is 

 beautifully illustrated in the instance of whinstone or basalt. A 

 piece of solid whinstone gave 80 deg. by the hygrometer; ano- 

 ther piece, rotten and crumbling, gave 86 deg.; but another por- 

 tion of the same rock, already reduced to mould, gave 92 deg. 

 The ameliorating effects of culture are exemplified in sea-sand. 

 Fine sand caused a dryness of 70 deg., and collected from a sheep 

 walk near the beach, 78 deg.; the same sand lately brought into 

 cultivation, 85 deg.; still these effects are inferior to garden 

 mould, which amounts to 95 deg., and to which decomposed 

 whinstone approaches the nearest. 



Mr. Leslie insures a plentiful and easy harvest to such as may 

 be inclined to pursue these investigations, which from their im- 

 portance and application to rural economy merit particular atten- 

 tion. It is to be hoped they will be resumed and prosecuted with 

 that success which has hitherto distinguished the researches of the 

 author of the preceding enquiries. — JYicholso7i's Journal, ISOL 



OPERA.TION or SEPTON ON PLANTS AND ANIMALS. 



BY DR. SAMUEL L. MITCHELL. 



[Opinions of 1796, as promulgated by Dr. Samuel L. Mitchell, 

 on septon (azote) and its compounds, as they operate on plants 

 as food, and on animals as poison; by which it is manifest that 

 the Doctor has forestalled many of the popular and scientific doc- 

 trines of the day, and for which due credit ought. to be awarded. 

 It is in the form of a letter from Dr. Mitchell to the Rev. Dr. 

 Henry Muhlenberg, of Lancaster, Pa., dated New York, Oct. 24, 

 1796. The letter to be sure is rather long, but it is well worth 

 reading, and many of our subscribers may not be able to procure 

 the work in which it is published. We therefore give the com- 



