48 MANURES. 



have been described by CHAPTAL as consisting of pure cal- 

 careous earth or lime, 30 parts; sulphuric acid, 32 parts; and 

 chrystallized water, 38 parts. It dissolves in about 500 times 

 its own weight of water, is reducible to powder in the fire, but 

 is almost as difficult of fusion as limestone, and loses by cal- 

 cination about 20 per cent. 



When pure, it does not effervesce with acids, is insipid to 

 the taste, and free from smell; but there are other sorts which 

 vary in purity, and hence the analysis of chemists may differ 

 in the accounts of its properties. There is, however, a very 

 simple method of testing its quality, common in the United 

 States, which consists in placing a quantity of it, pulverized, 

 into a dry pot over a fire, and when heated it gives out a sul- 

 phurous smell. If the ebullition, or bubbling, which then 

 takes place, is considerable, the plaster is good; but if not, it 

 is considered indifferent; and if it remains motionless like 

 sand, it is deemed worthless. 



We owe much to the late RICHARD PETERS, Esq., for the 

 enlightened zeal and perseverance with which, years since, he 

 laboured in introducing this valuable mineral to the favourable 

 notice of farmers, jn the face of the most violent opposition. 

 But all opposition was happily surmounted; and this valuable 

 substance soon assumed, and still occupies, its proper rank 

 among manures. 



The use of gypsum as a manure, though only within the 

 last few years brought into general practice, is not a modern 

 discovery, for traces of it are to be found in the writings of 

 the ancients. It was not, however, until about the middle of 

 the last century, that public attention was attracted to it, its 

 properties as a manure being then accidentally discovered in 

 Germany by a labouring hand, employed at a quarry of that 

 substance. This person (his name should have been preserved) 

 had occasion frequently to pass across a certain strip of meadow 

 to shorten his distance home; and being an observer of things, 

 he was struck with the luxuriance of the grass where he had 

 walked; and supposing it to be caused by the dust of the gyp- 

 sum from his feet and clothes, made experiments which verified 

 his supposition. 



JUDGE PETERS, in the Memoirs of the Philadelphia Agri- 

 cultural Society, vol. i. page 156, gives the following account 

 of its first introduction into the country: "The first I saw of 

 the agricultural effects of gypsum, was several years before the 

 commencement of the revolutionary war, on a city lot on the 

 commons of Philadelphia, occupied by JACOB BARGE. He 

 was the first person who applied the gypsum in America to 

 agricultural purposes, but on a small scale. 



