442 TRANSACTIONS OF THE AMEPJCAN INSTITUTE. 



Carbonic acid gas is always present in very small quantity, togetlier with a 

 trace'of ammonia. In cities the air is also tainted with sulphurous acid and 

 sulphuretted hydrogen. This last, like nearly all the compounds of hydrogen, 

 except water, is very detrimental to the human constitution. 



Sulphuretted hydrogen, or hydrosulphuric acid as it is sometimes called, is 

 formed on the water type, sulphur being substituted for oxygen. It is a color- 

 less gas, having a disgusting odor resembling rotten eggs. Even when mixed 

 with a thousand times its bulk of common air it can not be breathed by the 

 lower animals without fatal results. It is heavier than common air, 100 cubic 

 inches weighing a little over 38 grains, while the same bult of air weighs 31 

 grains. Under a pressure of 250 pounds per square inch, sulphuretted hydro- 

 gen is reduced to a colorless liquid, and at 122'' Fahr. below zero it is frozen 

 into a transparent solid. The gas is formed spontaneously. For instance, 

 where a soluble sulphate,, by contact with decaying' animal or vegetable mat- 

 ter, loses oxygen and becomes a metallic sulphide, which, in turn, is easily 

 decomposed, even by the little carbonic acid always present in the air, the 

 result being a metallic carbonate and sulphuretted hydrogen. 



The average composition of the atmosjihere is now given by the best autho- 

 rities as follows: Every 100 parts, by volume, contains 



Of oxygen gas 20.61 



Of nitrogen gas 77.95 



Of carbonic acid gas - .04 



Of water- vapor 1.40 



Of nitric acid and ammonia traces. 



Of sulphuretted hydrogen, in large towns traces. 



Of sulphurous acid, do do traces. 



Mr. T. D. Stetson admitted that noxious odors and gases frequently were 

 generated in some of the manufacturing establishments of the city, but he 

 dissented from the view of some that therefore these establishments should be 

 suppressed. They were here, as in many other cities, one of the causes of 

 our prosperity. 



Mr. Enos Stevens did not kn(jw M'here we should stop if we began to 

 exclude bad smells, and did not believe we should agree as to what smells 

 were bad. Some paid a great deal for smells that others thought bad. He 

 thought musk bad, and tobacco excessively nasty ; but others thought them 

 agreeable. There were others that -were offensive to those who cultivated a 

 dislike for smells that they believed to be bad, but were indifferent or imper- 

 ceptible to those who did not attend to them. It was all imagination ; they 

 don't care about smells,, except fancy smells that they pay for. Only the arti- 

 ficial people, who cultivate artificial miseries, are troubled by them, and they 

 enjoy their troubles. So no harm is done. 



Tlie subject was further examined by several speakers, and the conclusion 

 seemed to be that the most objectionable odor, that having a slight creosote 

 smell, was from the gas houses, and must arise at the time of discharging from 

 their purifying apparatus the lime saturated with various impurities. 



Dr. Parmelee made an interesting experiment with phosphorus dissolved in 

 turpentine. He explained how the phosphoric acid, generated in burning 

 phosphorus, acted as a protection against further combustion, and showed why 

 the general incendiary attempt on our principal hotels failed. After which he 

 o-ave the following account of: 



