16 On the Hydro- carlonated Gases. 



stands for their security) for hoiding solutions, &c. 

 exposed to ihe Voltaic conductor. The counnuni- 

 catioiis where more than one is used are made by 

 asbestos, 6i.c. 

 O and P. Vases or cups turned in gvpsum, chalk, or fluor 

 spar, and filled with water or coloured solutions, tor 

 the purpose ot exhihit:ng the decomposition of such 

 bodies, as belore mentioned. 



The apparatus and its appendages were constructed under 

 my direction by Mr. Bate, philosophical instrument-maker. 

 Poultry, London. 



IV. On the Difference hetween fhe Hydro- car lonattd Gases 

 extricated from Mineral a?id Animal Substances re- 

 spectively*. 



JVIessrs. Thenard and Dupuytren, within these two 

 or three years, made an experiment which has thrown 

 considerable light on the existence of miasmata. They 

 agitated distilled water with hydro-carbonated gas extri- 

 cated from mineral substances. This water, exposed to 

 the air and allowed to stand, was not disturbed, and gra- 

 dually got rid of its hydrogen gas without being corrupted. 

 The same experiment made with hydro-carbonated gas 

 coming from animal putrefaction presented another result. 

 The water became turbid, it contained flakes of a substance 

 truly aninnl, which was precipitated on being allowed to 

 rest, and the liquid was putrefied. Thus, all hough the gas 

 was the same to the eyes of the experimenter, the latter 

 coniained manifestly miasmata which gave rise to the flakes 

 observed, and to the putrefaction of the water. 



M. Moscati, an eminent Italian physician, has made 

 similar and'equally interesting experiments. Having ob- 

 served that the cultivation of rice in the humid rice grounds 

 of Tuscany was annually attended with epidemic diseases 

 and ddyiianiic fevers, he conceived the idea of asccrtainuig 

 the natuie of the vapours which rose from the ground where 

 rice was cuhivaltd : with this view he suspended at some 

 distance froin tlie ground hollow spheres filled with ice. 

 The vapours were condensed on the spheres in the form of 

 hoar frost. He collected this substance in flasks, in which 

 it melted and at first presented a clear liquid. Speedily it 

 was f\>..:id with small flakes, which when collected and anai 



* Anualtt dc Chimie, tonie bfxxii. p. 830, 



lysedj 



