346 Miss E. Johnstone and Prof. Thos. Carnelley. [Feb. 14, 



III. "Effect of Floor-Deafening on the Sanitary Condition of 

 Dwelling Houses." By Miss ETTA JOHNSTONE, University 

 College, Dundee, and THOS. CARNELLEY, Professor of 

 Chemistry in the University of Aberdeen. Communicated 

 by Sir fl. ROSCOE, F.R.S. Received February 7, 1889. 



" Deafening " is the material which is laid upon boards fitted in 

 between the joists of a floor to prevent the passage of sound into the 

 room below. This material is used largely on the Continent and in 

 many parts of this country, especially in Scotland, and is supposed 

 to consist of a mixture of coarse mortar and smith's ashes, but 

 in general it appears to be of a much more questionable nature, 

 particularly in the case of low-class houses. It is also supposed by 

 some builders to prevent the passage of smell; but houses are known 

 to have been rendered uninhabitable by its presence, the cinders, 

 which form the great bulk of the substance, being more or less 

 contaminated according to the place whence obtained and other 

 attendant circumstances. 



With the object therefore of ascertaining whether this material was 

 a serious factor in the pollution and vitiation of the air of dwelling- 

 houses, we undertook the analysis of a number of samples from 

 various classes of houses in Dundee, and the results obtained are 

 recorded in the present paper. 



Carnelley, Haldane, and Anderson ('Phil. Trans.,' B., vol. 178 

 (1887), pp. 61-111) have proved that the number of micro-organisms 

 habitually present in the air of a dwelling-house increases with the 

 age of a building. Indeed, some of the older buildings become 

 perfectly infested with them, as shown not only by the results 

 obtained by the above observers in houses and schools in Dundee, but 

 also by those of Miguel in old and new houses in Paris. Indeed, this 

 floor-deafening when impure would appear to be a remarkably good 

 medium for the propagation of bacteria, other conditions being 

 favourable. 



Dr. Emmerich, of Leipzig, some years ago (' Zeitschr. f.'.Biol.,' 1882) 

 made experiments on the effects of this stuff with regard to the air of 

 rooms, and also analysed numerous samples of pure material, some of 

 which were obtained from new buildings on completion, and some 

 from inhabited houses. He found that on washing the floors of 

 rooms, shutting them up for some time, and then examining the air, 

 there was a great increase of carbonic acid, which must have been 

 dne to the putrefaction set up by the moisture on reaching the 

 deafening, as all other known sources of carbonic acid were excluded. 



As a result of his investigations, he concluded that " there exists 



