CHEMICAL APPARATUS. 9 "7 



of the boiler ; and extending to the bottom on one side there 

 is a thermometer also passing through a stuffing box, air- 

 tight, the ball within the boiler, and the scale on the outside, 

 which has a stout glass shade to protect it from being 

 broken ; on the other side of the boiler there is a stop-cock 

 with a pipe that may be disconnected ; the boiler is sup- 

 ported on a brass stand, and the heat is applied by means 

 of a large spirit lamp beneath. To use, a small quantity of 

 mercury, about half a pound, is poured in, and the boiler 

 about half tilled with water, leaving the stop-cock open ; heat 

 the globe with the lamp till the steam issues from the pipe, 

 when the thermometer will stand at 212, but will immedi- 

 ately begin to rise, forcing the mercury up into the glass 

 tube, and when it has reached the height of thirty inches, 

 or the pressure of an additional atmosphere, the water will 

 be heated to a temperature of 250. Pour half a pound of 

 water into the boiler, and apply the heat till all is converted 

 into steam, having the pipe immersed in a vessel containing 

 five pounds of water, at 60, it will raise the temperature 

 of the five pounds to 160, or will boil a smaller quantity. 



Price, $15.00. 



Wollaston^ Steam Apparatus. (Fig. 560.) F3 - 660- 

 Is a small but neat contrivance of Dr. Wollas- 

 ton, to illustrate the principle of the condensing 

 steam engine. It is represented annexed, and 

 consists of a glass flask fitted with a belt out- 

 side, and handle screwed to the belt. Inside it 

 has a solid piston, working with little friction, 

 yet steam-tight, up and down. A little water 

 or ether is placed in the bulb of the flask and 

 made to boil ; the piston is then put in, and 

 the bulb being dipped for a moment in cold 

 water, the steam withinside condenses, and the 

 piston descends ; making the liquid boil a second time drives 

 up the piston, &c. ; thus the piston rises at every formation, 

 and falls at every condensation of the steam. 



Price, Si. 50. 



Calorimeter. (Fig. 561, next page,) An instrument for 

 measuring the quantity of heat contained in any body, the 

 temperature of which is above thirty-two degrees. It con- 

 VOL. n. 9 



