348 FUMIGATIONS TO DKSTROY CONTAGION. 



less active. Soon after this I was informed, that phials re- 

 cently bought of him scarcely made any impression on the 

 nose when opened under it; and some were brought nit", 

 from which I found in fact but a slight smell of common 

 muriatic acid. On my representing this immediately to 

 Mr. Boulay, he at once made his phials as strong as they 

 ought to be; and I know, that those he has since sold were 

 well prepared. This however suggested tome, that it might 

 be proper, to determine the process with more precision 

 than I had hitherto done, I mean with regard to weight and 

 measure, in order to have a liquid at all times manageable, 

 and of a permanent degree of activity. I shall proceed 

 therefore to give the receipt with all its particulars. 

 The phials de- The phials to be made portable should scarcely exceed in 

 scribed. capacity A\ centilitres [l|oz.], or 45 cubic centimetres 



[about 2 J cubic inches]. This is the measure of those pre- 

 pared by Mr. Boulay, who puts them into a case of hard 

 wood, commonly of box, neatly made. The cap of this 

 case screws on. It is unnecessary to say, that the stopple 

 of the phial must be of glass, and ground to fit perfectly 

 tight. 

 Method of pre- Having selected a phial, it is to be measured. Suppose 

 paring them ; ts capacity to be just 45 cub. cent. [Hoz.], 3 gr. [46-32 

 grains] of black oxide of manganese are to be put into it, 

 * powdered, but not finely, and sifted only through a hair 

 sieve. 



To these add 7-5 cub. centim. [about {of a cubic inch] 



or | of a centilitre [| of an oz.] of pure nitric acid of the 



specific gravity of 1*4 (about 39° of Baume's areometer), 



and an equal measure of muriatic acid of the specific gravity 



of 1*134 (about 17° of Baume's areometer). 



The stopple being put in, the process is finished. 



They must not I* ' s *° 0e observed, that about two thirds of the capacity 



be more than f the phial will thus remain empty. This is an essential 



condition, without which it is impossible to confine the gas. 



Having once exceeded this proportion in a very strong ilint- 



glass phial, that would hold 4 decil. ,[13 oz.], I saw the 



stopple, which weighed 122 gram. [1881 grs.], driven out 



to such a height, that in falling it broke the phial. But it 



is easy to prevent all accidents, by keeping within the limits 



here assigned. 



It 



