Temperatures, as suggesting a Substitute for Quaratitine. 365 



bable that increased heat produces no change either in the 

 number or propoiiions of the atoms of the substances ; but 

 that, in some way which chemical science has not yet pre- 

 pared us to explain, it modifies only the arrangement of the 

 atoms, and thus confers new distinctive characters. 



In pursuing the inquiry experimentally, two circumstances 

 seemed to me to require to be established. 



1st, That raw cotton, and other substances likely to har- 

 bour contagion, would sustain no injury by the temperature 

 conceived to be necessary for their disinfection. 



2ndly, That in at least some one unequivocal instance, con- 

 tagious or infectious matter should be proved, by actual expe- 

 riment, to be destructible at that temperature. 



I. To ascertain the first point, I submitted in August 1824, a 

 quantity of raw cotton to a dry temperature of 1 90°Fahrenheit, 

 which was steadily kept up in the inner compartment of a 

 double vessel heated by steam, during two hours. When the 

 staple of the cotton was examined by Mr. Garnelt, lie pro- 

 nounced it to be so essentially injured, as to set at rest, on a 

 first view, all intentions of adopting this method of purifica- 

 tion. The same unpromising appearance was presented also 

 by cotton yarn, which, after being spun, had been heated 

 during two hours at 190° Fahrenheit. After being allowed to 

 cool during a quarter of an hour, it was compared with yarn 

 of the same fineness which had not been heated, with the fol- 

 lowing result : 



lbs. avoird. 



A hank of mule twist (40 to the pound) not heated, ) c^Af-x 

 required a weight, to break it, of ) * 



A hank of ditto ditto heated to 190° and 1 ,„„2 

 just cooled /^^^3 



The strength of the yarn, measured by its power of sup- 

 porting weights, had therefore suffered a diminution, by being 

 heated, of fuiiy one-third. The remainder of the yarn so heated 

 having been laid aside in a cellar, was accidentally examined 

 on the fourth day, and had undergone an obvious alteration, 

 which led to a renewed trial of its strength. It was now found 

 that a hank of the same yarn supported a weight of 241^ 

 pounds, and it had therefore recovered very nearly its original 

 tenacity. 



At this period I was obliged, by unavoidable circum- 

 sUmces, to abandon the inquiry; and the inducement to re- 

 sume it ceased in a great measure to exist, in consequence 

 of the discontinuance, for a season, of the pressing inconve- 

 nience which had given birth to it. It was only recently that 

 my attention was recalled to the subject by the well grounded 



alarm 



