426 EXPERIMENTS ON 



from its prefence, but as they did not detect it by any teft 

 with which we are acquainted, tlieir opinion is entirely 

 hypothetical. 



The following are the refults of the means I employed 

 to difcover whether ammoniacal gas is prefent in the at- 

 mofphere of marflies. i. No white clouds appeared, when 

 muriatic acid gas was mixed with air obtained by agitating 

 ilagnant waters. 2. Slips of paper ftained yellow by turme- 

 ric, were fufpended in a bottle containing mud and atmof- 

 pheric air, it remained unchanged ; whereas thofe ftained 

 with litmus received a reddiili tinge. 3. I never could per- 

 ceive the odour peculiar to this alkali, when 1 vifited marfhes. 



The above experiments caufed me to doubt the prefence 

 of this elaftic fluid in the atmofphere of marflies. I was 

 confirmed in this opinion by the following circumftances : 

 I ft. Ammoniac combines readily with water : it is impoffi- 

 ble to procure ammoniacal gas over water ; therefore we arc 

 to fuppofe that if this fluid is produced it is immediately 

 abforbed by the water of the marfli. 2dly. Carbonic acid 

 gas is abundant in the atmofphere of marfhes. By experi- 

 ment, 1 afcertained that this acid and ammoniacal gas were 

 very prone to unite and form the carbonate of ammoniac. 

 The experiment was peiformed in a glafs tube over m.ercu- 

 ry : as foon as the two elaftic fluids came in contadt, an ab- 

 forption took place and the bulk of them was confiderably 

 diminiflied : at the fame time the fides of the tube were in- 

 crufted with a white matter, which poffefled all the pro- 

 perties of the carbonate of ammoniac. If fuch are the phe- 

 nomena of thefe experiments, why will not fimilar effects 

 take place in marlhy fituations ? 



4. Nitric acid. The experiments and obfervations of 

 Thouveel and others, have long fince demonftrated the 

 prodiidlion of this acid during putrefadion. If it is form- 

 ed in marfhy fituations, its prefence cannot be proved in 

 their atmofphere, and I ain inclined to believe that it is im- 

 mediately abforbed by the neighbouring waters. 



5. Sulphurated 



