^98 Apparatus for Solidifying Carbonic Acid. 



The generator A is made of a common mercury flask, several 

 of which I have tested and find sufficiently strong. They may 

 be purchased in New York for a dollar a piece, or even less. The 

 aperture at the neck may be a little enlarged, so as to make it an 

 inch or an inch and a quarter in diameter, and the thread of the 

 screw re-cut. A plug of cast-steel B is made of a bar two inches 

 in diameter, and turned with a wide and smooth shoulder, so as 

 to fit accurately upon a collar of block- tin when screwed into its 

 place, as represented in the figure. This collar should be sol- 

 dered to the iron ; which is easily accomplished by filing the iron 

 bright and tinning it in the ordinary manner, and then melting 

 the block-tin and pouring it on, having first screwed a cork into 

 the aperture and formed a wall of putty or clay at a sufficient dis- 

 tance around it. The shoulder of the plug is readily made to fit 

 the collar accurately by screwing it a few times into its place, 

 and then removing with a coarse file the parts of the collar upon 

 which it touches. In this manner an accurate joint may be made 

 without the use of a lathe ; and if the plug does not correspond 

 precisely with the axis of the flask it is just as well. 



The faucets or stop-cocks are the most difficult part to con- 

 struct, and occasion full half the expense. These in our appara- 

 tus are supposed to be essentially the same as are used by others 

 for this purpose, but it may not be amiss to insert a description, 

 since none has to my knowledge been given. There is this pe- 

 culiarity about ours, however; they are inserted in the cast-steel 

 plugs, which indeed make a part of them. D is designed to rep- 

 resent the plug removed from the generator ; at the upper end of 

 it a hole P one inch in diameter is drilled about an inch deep, 

 terminating in a hollow cone into which the point G is accu- 

 rately ground. A small hole extends quite through the plug. 

 Around the aperture F a collar of block-tin is fitted to receive 

 the shoulder of the part E, as seen at I, and prevents any pas- 

 sage around the threads of the screw. Through the axis of the 

 part E a hole three eighths of an inch in diameter is drilled, and 

 receives the part G w^hich is screwed in from below, the handle 

 H being removed. The handle H should be afterwards riveted on. 



Now suppose H E G to be inserted in its place in the cast- 

 steel plug, as represented at B I, the plug itself being screwed 

 into the generator. If H' be screwed down, the aperture from 

 the generator is firmly closed by the conical point G ; and by giv- 



