1870.] On the Method of Assaying Silver. 393 



porting) table for conducting away the fluid syphoned from each 

 set of bottles. 



5. The trough is a basin of cast iron (painted), it may be oblong 

 or round, raised to about the height of 3 feet from the ground ; 

 when round and large enough for 20 bottles, space and distilled 



-water may be economised by having a platform insulated in the 

 centre. This is convenient for resting the bottles on after the 

 chlorides have been got out. A trough of this kind may be about 

 2J feet in diameter, having a space 7 inches broad and 4 deep all 

 round between the circumference of the basin itself and the outer 

 edge of the island platform. Into this space is poured distilled 

 water to the depth of 3 inches. From the rim of the trough hang 

 as many brass supports as there are bottles to be inverted, these 

 are two circular clasps connected at the back to a bar common to 

 both : one, the larger, is 1^ inch above the smaller and lower one 

 which is under water ; they are open in front (or towards the centre 

 of the basin) to about f of an inch in width. The openings of 

 both are in the same line owing to the lower (smaller) segment 

 being projected towards the centre by an abrupt curve in the con- 

 necting bar, by which they hang from the brim. This arrangement 

 receives and fixes the inverted bottles in the required position. The 

 distilled water is removed from the trough by the withdrawal of a 

 plug. These troughs are sometimes made to revolve on the centre. 



6. The drop bottle used for washing down the glass rod when 

 breaking up the chlorides, and for sprinkling the surface of the 

 cups, is small sized, round, so as to be easily grasped ; it holds 

 about six ounces. The stopper is hollow, with 2 small tubes lead- 

 ing from its head, one opposite to the other. Glass is so liable to 

 break or chip, that a hollow silver stopper is now generally sub- 

 stituted. 



7. The steam-bath is simply a square vessel made of sheet 

 copper, between three and four inches deep, the top or upper plate 

 of which has a number of circular openings about two-thirds of 

 the diameter of a wedge-wood crucible. There is also a steam 

 escape pipe leading from the centre below to about a foot in height. 

 They are of various sizes to contain from 10 to 150 pots : they are 

 raised or moved by two lateral handles. 



