1847.] Extracts from the Older Journals. 279 



are of opinion, that in order to make the whole subject well un- 

 derstood, there should be a set of correct and well conducted ex- 

 periments, on the actual composition and relative properties of 

 the several sorts of plaster. But who that can be relied on will 

 undertake this inquiry? 



Further Facts tending towards an Explanatimi of the true Opera- 

 tion of Alkalies and Lime upon other substances. In a letter 

 from Dr. Mitchell to Thomas Beddoes, M. D., dated JYew York, 

 September 15, 1797. 



What I wrote to Dr. Percival on the 17th of January, 1797, 

 was an attempt to reduce the phenomena of alkaline remedies and 

 neutral salts, in febrile distempers, to a general principle, by shew- 

 ing how they overcame or expelled the putrid miasmata, or the 

 contagion which induced the symptoms. Since that time, when 

 in the spring of the present year, it w^as agitated among the citi- 

 zens of New York, whether manufactories of soap and candles 

 generated pestilential air, the facts which presented themselves to 

 my view led to a conviction, that calcareous earths, alkaline salts, 

 animal fats, and vegetable oils, attracted the matter which im- 

 parted to the atmosphere its epidemic and sickly influence, and, 

 consequently neutralized or deadened the septic effluvia which 

 were the cause of fevers. (Case of the manufacturers, &c., stated 

 and examined.) And more recently still, on considering these 

 noxious exhalations, in relation to soils, manures, and vegetation, 

 it seemed obvious, that lime and alkalies could repress them; and 

 by so doing, did purify the air and fertilize the land; and were 

 thus serviceable in agriculture, not by any septic influence they 

 possessed, but, in a considerable degree, by neutralizing the septic 

 or acid of putrefaction. (Medical Repository, p. 39.) Indeed, 

 the united force of the facts afforded by the materia medica, by 

 arts and trades, and by agriculture, prevailed over all the tbrraer 

 notions I possessed; and, as I believed, did exhibit in evidence 

 too strong to be resisted, that the principle I had laid down was 

 grounded upon a very broad induction of facts. 



Besides the considerations alluded to, my opinion of the power 

 of lime to absorb, and, in some degree to neutralize the fluids pro- 

 duced by putrifying animal substances, was strengthened by read- 

 ing Grayden's paper concerning the lishes inclosed in the lirae^ 

 stone of Monte Bolca, near Verona. (5 Trans, of the Royal 

 Irish Academy, p. 281.) Here is a mass, or part of a stratum of 

 calcareous rock, which contains, not the mere impressions or like- 

 nesses of animals, as shistic fossils commonly do, nor petrifactions 

 of them, as is generally the case with calcareous rocks, but the ac- 

 tual remains of dead fishes, of their natural size and figure pre- 

 served like mummies, and so complete that their genera and spe- 



