104 THE MICROSCOPE AND HOW TO USE IT. 



rated, the excess of chlorine will accumulate in the bottle above 

 the hquid, and find an exit through the notch in the cork. As to 

 the time required for bleaching, this will vary in accordance with 

 the nature of the sections operated upon. As a rule, if the 

 apparatus be set to work at night, putting it out of doors in a 

 covered place to avoid the smell of escaping chlorine, the bleaching 

 will generally be found to be complete in the morning ; if not, 

 further time may be allowed without any danger to the sections 

 being incurred. 



Washing the Sections. — Decolouration having been effected, 

 nothing now remains but thoroughly to wash the sections, for it is 

 necessary to eliminate all trace of chlorine before employing any 

 staining agent. The usual method is to put the sections into a large 

 basinful of water, and to repeatedly change the water. Dr. Marsh's 

 way is much the best — i.e.^ continuous washing. Asmall, wide-necked 

 bottle (C), similar to those already described, must be procured. 

 Into the side of this, half-an-inch or so below the bottom of the cork, 

 a small hole, about an eighth of an inch in diameter, must be drilled 

 (any tinman will do this for a few pence). A well-fitting cork being 

 provided, this must be pierced through the centre, so as to allow 

 the stem of a small funnel to pass through it. By means of 

 small India-rubber tubing (feeding bottle-tube), the funnel-stem is 

 to be prolonged till it reaches the bottom of the bottle on the 

 side "which is opposite to that side containi?tg the perforation. 

 All being ready, half fill the bottle with filtered water and put the 

 bleached sections into it. Fit in the cork carrying the funnel, and 

 place a disc of filtering paper into the funnel ; put this beneath the 

 water-tap, and allow a gentle stream to trickle into it. The water 

 will pass to the bottom of the bottle, gradually ascend, and then 

 pass out at the hole in the side, by which means a constant change 

 of water and a continuous washing system is established. Do 

 this at night. Set the tap running when you go to bed, and the 

 washing will be effectually accomplished by the time you get up 

 in the morning. 



* This process was described in No. 43 of the " QuekeLt Journal," 

 p. 54, &c. 



