CHEMICAL APPARATUS. 



105 



When the aerated water is required for use, it is drawn off 

 by the tap, F. Price, $15 to $20. 



Ohristisons Apparatus for 

 detecting Poisons. (Fig. 574.) 

 A is an instrument for reduc- 

 ing the sulphurets of some of 

 the metals by a stream of hy- 

 drogen gas. B is a funnel- 

 shaped tube, for testing mi- 

 nute portions of liquids. C, 

 a tube for reducing a small 

 quantity of mercury. D, a 

 tube for taking up a minute 

 globule of ditto. E, bottle c 

 and tube for washing down 

 scanty precipitates or filters. F, apparatus for the distillation 

 of fluids, supposed to contain acids. Price, $4.00 to $5.00. 



Marsh's Arsenic Apparatus. (Fig. 575.) 

 This little instrument is effectual in detecting 

 the most minute quantity of arsenic in any so- 

 lution. It is composed of a bent glass tube, 

 slightly widened at both ends, one area of it 

 being three or four inches longer than the 

 other. Into the shorter arm a small piece of 

 zinc is dropped ; a thread should be attached 

 to it so that it shall not quite reach the bottom 

 of the tube. The liquid suspected to contain 

 arsenic has a little sulphuric acid mixed with 

 it, and a portion is poured into the arm B. 

 The stop- cock being open, the liquid will fully 

 occupy A ; but hydrogen gas being formed by the contact 

 of the acid and zinc, this will ascend ; and the stop-cock 

 being closed, it will accumulate. Upon being let off and a 

 light applied to the jet of the cock, the arseniuretted or com- 

 mon hydrogen, as the case may be, will be lighted ; if it be 

 the former, that is, if arsenic be present, it will tinge with 

 a purplish metallic stain a piece of glass held close over it ; 

 with common hydrogen, no stain will be perceptible. 



Price, $2.50. 



