APPENDIX III. 



REAGENTS AND MOUNTING MEDIA USED IN THIS WORK, 1 AND 

 HOW TO PREPARE AND USE THEM. 



ALL the reagents and mounting media in this list can be obtained, ready 

 made, of Messrs. Southall Bros. & Barclay, Manufacturing Chemists, Bir- 

 mingham, or of Dr. George Griibler, Leipzig, Dufour-Strasse, No. 17. Or 

 the materials can be obtained from the same sources, and the student will 

 find in this Appendix instructions how to prepare them for use. It is 

 hoped that the instructions are sufficiently explicit, but the editor will be 

 glad to have errors or inefficient descriptions pointed out to him. 



Percentage solutions are made either by weight or volume ; or, if the 

 metric system (see Appendix I.) is used, by, within certain limits, either 

 indiscriminately. Thus, 1 per cent, acetic acid in water is made by taking 

 1 volume acetic acid and adding to 99 volumes distilled water ; 5 per cent, 

 potash solution, by taking 5 grammes potash and adding to 95 c.c. distilled 

 water (1 gramme weight of water = I cubic centimetre volume). 



A saturated solution can be secured by seeing that some of the salt, etc., 

 is always lying undissolved at the bottom. 



Further information as to the uses of the reagents will be found by 

 reference to the general index. 



N.R For all purposes where alcohol up to 90 per cent, is used (i.e., 

 "alcohol," not "absolute alcohol,") strong methylated alcohol will serve. 

 Its alcoholic strength varies from about 85 to 90 per cent. Percentage 

 compositions can therefore be made with it instead of absolute alcohol. 

 Approximately 50 per cent, alcohol - 56 parts strong meth. ale., 44 water. 

 60 per cent, alcohol = 67 parts meth. ale., 33 water. 

 70 per cent, alcohol = 78 parts meth. ale., 22 water. 

 82 per cent, alcohol = 91 parts meth. ale., 9 water. 



(As this is a rather special strength it is best prepared 



with absolute alcohol.) 



90 per cent, alcohol = strong methylated alcohol. 



If possible "old style" methylated spirit should be obtained, as it 

 alone mixes freely with water. 



1 1 have added a few others of approved utility. 



(475) 



