154 ON THE CHEMICAL PROPERTIES OF SILK. 
« the virtues of cleansing the blood, making the 
spirits brisk, and the heart pleasant.” 
It is said, that if a thin silk veil is worn in 
countries where malaria is generated, that it will 
have the effect of counteracting its noxious qua- 
lities. 
The water in which cocoons are immersed prepa- 
ratory to reeling, acquires such a strong lathery 
consistence, that air-bells may be made with it, 
which are so flexible and strong that they have been 
known to remain without bursting for upwards of 
twenty-four hours. These bells exhibit the pris- 
matic colours in as high a degree as those formed of 
soap-suds. 
Count Rumford observed, that raw silk has a 
remarkable power of producing pure air from water. 
He found that, by introducing thirty grains of this 
substance, first washed in water, into a thin glass 
globe, four inches and a half in diameter, having a 
cylindrical neck three-fourths of an inch wide, and 
twelve inches long, inverting the globe in a jar 
filled with water, and exposing it to the action of 
the sun in the window; in less than ten minutes 
the silk became covered with an infinite number of 
air-bubbles, gradually increasing in size, till, at the 
end of two hours, the silk was buoyed up by their 
means to the top of the water. They separated 
themselves by degrees, and formed a collection of 
