54 Dr. J. Stenhouse on the applications [March 2, 



charcoal would be equally eftectual in absorbing the very minute 

 quantity of infectious matter floating in the atmosphere of what are 

 called unhealthy situations. This led him to the construction of the 

 so-called Charcoal Air-filter, first exhibited and described by him 

 before the Society of Arts, on the 22nd of P'ebruary, 1854. It con- 

 sists of a thin layer of charcoal powder, enclosed between two shee s 

 of wire gauze. One of these air-filters, or charcoal ventilators, was 

 erected more than three months ago in the justice-room, at the 

 Mansion-house. This apartment, from the 'position of several 

 nuisances in the very narrow street from which it is ventilated, 

 was usually so offensive as to have become the subject of general 

 complaint. Since the erection of the charcoal ventilator, through 

 which all the air entering the apartment is made to pass, all the 

 impurities are absorbed, and the atmosphere of the room has 

 become unexceptionable. From the success attending on the char- 

 coal ventilator at the Mansion-house, the City authorities have fitted 

 up the justice-room at Guildhall with a similar apparatus, which is 

 giving equal satisfaction. The charcoal ventilator at the Mansion- 

 house has never required any alteration, such as renewal of the char- 

 coal, or otherwise. Charcoal ventilators cannot fail to prove 

 eminently useful in all situations where foul air is apt to accumulate, 

 such as in water-closets, in the close wards of hospitals, in ships, 

 and in the back courts and mews-lanes of large cities, all the im- 

 purities being absorbed and retained by the charcoal, while a current 

 of pure air alone is admitted into the neighbouring apartments. 

 In this way pure air is obtained from exceedingly impure sources. 



A short sketch was then given of the history and construction of 

 Eespirators, from their first proposal by Dr. Beddoes of Bristol, in 

 1802, till their description, some seventeen or eighteen years ago, 

 by Dr. Arnott, in a lecture at the Royal Institution, and their being 

 subsequently patented by Mr. Jeffreys, who first brought them into 

 general use. Mr. Jeffreys' and the ordinary respirators are intended 

 merely to warm the air ; but the charcoal respirators, especially 

 those which embrace both the nostrils and mouth, purify the air by 

 filtration, and thereby deprive it of the noxious miasmata which, in 

 unhealthy situations, it not unfrequently contains. Experience has 

 shown, however, that charcoal respirators not only purify the air, 

 but warm it sufficiently, while they possess several advantages over 

 the ordinary respirators. Thus, for instance, they are lighter and 

 more easy of construction ; and where the breath is at all foetid, as is 

 usually the case in diseases of the chest, throat, &c. the disagree- 

 able effluvia are absorbed by the charcoal, so that pure air alone is 

 inspired. The charcoal respirators are also exceedingly easy to 

 breathe through, as, owing to the non-conducting nature of their 

 material, they do not condense the moisture of the breath to an 

 inconvenient extent. There are three forms of the charcoal re- 

 spirator, one for the mouth alone, tlie others embracing both the 

 mouth and nostrils ; these two latter forms being specially intended 



