DESICCATION 



15 



No. 3 exposed to the atmosphere for throe weeks, weighed at the end of that timo 

 J 7-8, or had taken in 4'2 per cent, of moisture. 



Feathers. Feather beds, mattresses, blankets, and clothing, are not only dried, but 

 purified by this process. A feather bed of sixty pounds weight will have no less than 

 1 00,000 cubic feet of air passed through it ; and at the same time beaters are made 

 use of, for the purpose of removing the dust. Feathers treated in this manner have 

 their bulk and elasticity so much increased, that a second tick is found almost inva- 

 riably necessary to put the feathers into. 



A practical proof of the extreme powers of currents of dry heated air was given in 

 Syria, by exposing to them sixty suits of clothes, which had belonged to persons who 

 died of the plague. These clothes were subjected to the process alluded to, at a tem- 

 perature of about 240, and afterwards worn by sixty living persons, not one of whom 

 ever gave the slightest symptom of being affected by the malady. (Whishaw.) It has 

 been proposed to dry coffee by currents of heated air, and subsequently to roast it by 

 the same process. 



Thick card-board, used for tea-trays and papier-mache, is now frequently dried by 

 heated air. By the plan adopted at one establishment, previously to the introduction 

 of Davison and Symington's method, it invariably occupied from eighteen to twenty 

 hours to dry a room full of paper by a heating surface equal to 330 feet ; whereas by 

 the new method, the same amount of work is accomplished in four hours, and with a 

 heating surface of only 46 feet, or one-seventh the area required by the former. 



Silk. For the purpose of drying silk, it has been usual to heat the drying chambers 

 by large cast-iron globular stoves, the heat obtained thus was equal to 120 F., but 

 excessively distressing to any stranger entering these apartments. 



In one arrangement 7,000 cubic feet per minute are admitted at the above temper- 

 ature through small perforated iron plates, let into the stone floor. As many as 3,000 

 pieces of silk are sometimes suspended at one time : and as each piece of silk, when 

 wet, contains about seven ounces of water, and as the operation of drying the whole 

 occupies but one hour, it follows that about 130 gallons of water are evaporated in 

 that time. 



Yarns. In Scotland and other places they now dry yarns by modified applications 

 of this process ; and it is indeed extensively used in bleaching establishments, in 

 calico-printing works, &c. See Transactions of the Society of Arts for 1847-8. 



A DRYING HOUSE is an apartment fitted up in a peculiar manner for drying calicoes, 

 and other textile fabrics. Mr. Southworth, of Sharpies, a Lancashire bleacher, obtained 

 a patent in 1823, for the following ingenious arrangement, which has been since gene- 

 rally adopted, with certain modifications, in most of our extensive bleaching and 

 printing works. Fig* 599 is a section of the drying-house, where a is a furnace and 



boiler for the purpose of generating steam ; it is furnished with a safety valve in the 

 tube b, at top, and from this tube the steam-main c passes down to the floor of the 

 basement story. From this main, a series of steam-pipes, as d d, extends over the 

 surface of the floor, and from them heat is intended to be diffused for the purpose of 

 warming the drying-house. 



