36 



LIQUID MEASURES. WASHING-BOTTLE. 



quantities of water. To perform this operation conveniently a 

 washing-bottle is required, and a support for suspending your 

 balance at some height. The wooden support, fig. 35, is best 



FIG. 35 (an. proj. real size). 



made by a joiner ; it is very useful for many experiments. The 

 foot should be at least 80 cm long, 20 cm wide ; the frame 60 cm in 

 height and width ; the bars themselves should be of hard wood, 

 2 cm square. If the whole can be made somewhat larger it is so much 

 the better. Into the upper crossbar a number of small iron or 

 brass hooks are screwed, which may be bought at any ironmonger's. 

 A hole$ smaller than the screw, is first made with a gimblet, and 

 the screw is slightly greased with tallow, before it is screwed into 

 the hole. 



The washing-bottle is used for producing a fine jet of water. 

 A flask, usually of the form shown in fig. 36, has two tubes 

 adapted to it air-tight, by means of a twice perforated cork. The 

 tube a is bent at an obtuse angle, the tube b, which reaches nearly 

 to the bottom of the flask, is bent at an acute angle, and ends 

 externally in a fine point, having an aperture of only about O mm '5. 

 This extremity should not be too thin in the glass ; it is therefore 

 better to make the tube very hot before drawing it out, and to 

 draw it out only about as far as shown in fig. 37. The narrow 

 portion is then cut by the file in the middle, and broken off. The 



