most effectual means of destroying poisonous matters ready 

 formed; while the addition of those commonly known by 

 the name of antiseptics, would, by arresting putrefaction, be 

 the most useful to prevent their formation. The action of 

 the former depends on the facility with which they extract 

 hydrogen from any organic compound, and thereby so far 

 alter its composition as to destroy its former properties. 

 Now, as we cannot very well conceive the existence of an 

 organic product of putrefaction, similar to those which 

 constitute the miasms of marshes, &c., to be free from 

 hydrogen, it is clear that such agents are effective. Chlorine 

 we may consider to be one of the most powerful oxydizing or 

 dehydrating substances we possess, and as such it destroys 

 organic colouring matter, or odours arising from sulphuretted 

 hydrogen, phosphuretted hydrogen, and other products of 

 putrefaction. It is best used in the state of chloride of 

 lime, a small portion of which, dissolved in water, will, by 

 absorbing carbonic acid from the air, liberate chlorine slowly 

 and gradually, though in sufficient quantity to purify the 

 atmosphere of apartments receiving the exhalations from 

 such sources as those above named. The same substances, 

 mixed with the contents of cesspools, &c., would, as long as 

 any chlorine remained, prevent the liberation of any injurious 

 compounds ; but in consequence of this material being rather 

 expensive, other oxydizing agents have been proposed, and 

 employed with advantage in its stead. A person named 

 Ellerman has recently patented a persalt of iron as a dis- 

 infecting agent, which certainly decomposes noxious gases, 

 and will probably destroy the really injurious substances 

 which accompany them, if applied in sufficient quantity. 

 As long as any persalt of iron existed in a mass of organic 

 matter, decomposition would be very much impeded, if not 

 entirely stopped ; while any injurious matters generated 

 before its addition would be entirely destroyed. Nitric acid. 



