APPARATUS 3 



liquor iodi of the Pharmacopoeia ; or as follows : dis- 

 solve a small quantity of potassium iodide in distilled 

 water, and add crystals of iodine : if the solution be 

 too deeply coloured it may be diluted with distilled 

 water to the colour of brown sherry. 



*e. Chlor-zinc-iodine (Schulze's solution) may be pur- 

 chased ready prepared from the dealers in micro- 

 chemical reagents : or it may be prepared as follows : 



(1) Dissolve 110 grms. of zinc in 300 c.c. of pur 



hydrochloric acid, and evaporate to 150 c.c. 

 (sp. gr. about 1-8). 



(2) Dissolve 12 grms. of KI in as little water as 



possible : add 0'15 grm. of iodine. 



(3) Mix (1) and (2), and filter, if necessary, through 



asbestos. The solution should have a dark 

 sherry-brown colour. 



*/. Solution of aniline chloride : a saturated solution is 

 made in distilled water, filtered, and a few drops of 

 hydrochloric acid added so that it may give a dis- 

 tinctly acid reaction. The solution should be colour- 

 less. 

 *g. A solution of common salt : a 5 per cent, solution, 



i.e. 5 grins, of salt to 100 c.c. distilled water. 

 Many other reagents besides these will be required for the 

 work described below : also substances for permanent mounting 

 and sealing up of slides : their preparation and uses are detailed 

 in the Appendix A. 



Care should be taken in the preparation of the reagents : they 

 must be kept pure, and should be renewed occasionally. Glass 

 rods with rounded ends are to be used for removing drops of the 

 reagents from the bottles to the slide, and the rod should always 

 be cleaned before dipping it into a reagent-bottle. 



*24. Two wash-bottles such as are in ordinary use in a 

 chemical laboratory : the one should contain alcohol (methyl- 

 ated), the other distilled, water. 



B 2 



