F. A. Gooch — Forms of Laboratory Apparatus. 241 



ing, with the lower end of the vertical branch bent to make a 



water-trap, while the horizontal branch is connected with the 



steam supply. A pipe to convey away the condensed water 



which overflows from the trap is a convenience, but in the 



absence of a drip-pipe any suitable receptacle 



may serve a similar purpose. Ordinary 



water-bath rings adapt the funnel to vessels 



of various sizes, but the funnel itself serves 



efficiently in holding several different sizes 



of round-bottomed dishes. The transparency 



of the funnel makes it possible to regulate 



the steam supply so as to secure the maxi 



mum heating effect without saturating the 



surrounding atmosphere with waste steam. 



Of course, if it is desirable, several of these 



steam-baths may be hung to the same rod. 



Mercury washer. — Various forms of mercury-washing ma- 

 chines have been proposed and used with success. The par- 

 ticular form here described and shown in fig. 5, differs essen- 

 tially from its predecessors only in the degree of fineness to 

 which the impure mercury is reduced when it is brought into 

 contact with the purifying medium. In this apparatus the 

 impure mercury, liquid, enough to flow readily, runs of its 

 own weight from the uppermost funnel through the supply 

 arm of a glass atomizer through the other arm of which com- 

 pressed air is admitted in force sufficient to break the thin 

 stream of mercury to 

 fine dust. Thus thor- 

 oughly comminuted, 

 and presenting the max- 

 imum surface to the 

 liquid, the mercury 

 falls into dilute nitric 

 acid, from which it 

 passes to distilled water, 

 and thence to the dry 

 receiver. Funnels* 

 fitted with outlet tubes 

 set in rubber stoppers, 

 as shown in the figure 

 answer well for contain- 

 ing vessels, and the 

 rod and socket device 

 described above serves 

 as a support for the y 



apparatus. In the case ^ 



of the particular appa- 

 ratus which I have used 



Am. Jour. Sci. — Third Series, Vol. XLIY, No. 261.— September, 1892. 

 16 



