Mr. J. Napier 07i Damp Walls. 339 



two inches of the depth of the wall lose half this moisture the first year, 

 then there will be upwards of 100 gallons water evaporated in a house 

 unprovided with proper means of ventilation, subjecting the tenants to 

 an incipient vapour bath, in which are dissolved the noxious gases gene- 

 rated in the family. Clothing in such an atmosphere also imbibes mois- 

 ture, and becomes damp, so that to contemplate the whole circumstances 

 only increases surprise that fevers, consumptions, and other diseases are 

 not more prevalent, and instead of the rate of life of that class being 20 

 years less than the upper classes, the wonder is that they can rear their 

 own offspring at all. 



The new houses built for the wealthier class, are constructed so that 

 the damp is not so great during the first and second years. The stone 

 walls are battened, leaving a stratum of air between the wall and plaster, 

 so that the plaster dries sooner. Brick partitions are however in the 

 same state as common houses, the plaster being put on the wall. Such 

 houses are all papered, which renders the evaporation less apparent and 

 slower, but withal the plaster absorbs the moisture from the walls ; not- 

 withstandmg the very thin stratum of air intervening, the paper and all 

 upon it absorb damp and evaporate freely, except those parts covered, 

 as will be manifested by mould and damp under places where pictures 

 hang close upon new walls, and this constant evaporation is not good 

 especially m sleeping apartments. The damp causes decomposition of 

 paste and paper, producing a bad smell, and a very unhealthy atmo- 

 sphere. The damp walls I have just described originate from the natural 

 moisture in the materials used, and are cured by time as the matters dry. 

 But there is a class of damp walls very common and destructive to 

 health, which no time cures. These are mostly in first floors of houses, 

 and originate from the foundation and the absorbing property of the 

 materials. After the drought of summer these waDs become compara- 

 tively dry, but whenever wet weather sets in, immediately the damp begins 

 at the floor and ascends gradually until it reaches from four to six 

 feet high, and there it comes and goes for several inches up or down 

 according to the weather, until the return of the summer. In the work- 

 ing man's house this is visible by a dark hne along the plaster, and we 

 have often seen that line fringed by a slight efflorescence. Such apart- 

 ments always feel cold. In the winter, fires are increased, and so is the 

 moisture, producing to an unlimited extent all the evils I have referred 

 to in new houses. In a papered house the evils are the same as formerly 

 described, although not so great as on walls without paper, except 

 smell. In a short time the paper loses its attachment to the plaster, and 

 falls off. Canvas is often used under the paper to prevent the loosening 

 of it, but that will not prevent the evils of damp. We have already 

 referred to layers of slate being put above the found as a good preventive 



