APPENDIX 1. 45 



For dilution by weight of an alcohol of known percentage the following 

 calculation may be used. — If A is the percentage by weight of the alcohol 

 to be diluted and B the percentage of alcohol required in the new mixture ; 

 to obtain the desired result add A minus B parts by weight of water to B 

 parts by weight of alcohol. 

 E.g. to make 50% alcohol from 95 % alcohol add 45 (= 95-50) grammes of 

 water to each 50 grammes of 95 % alcohol. 



To make 40 % alcohol from 70 % alcohol add 30 grammes of water 

 to 40 grammes of 70% alcohol. 

 Large or small quantities can be made by using different units of measure- 

 ment. The rule given here is correct for dealing with quantities and per- 

 centages measured by weight, but not for percentages measured by volume. 



FORMALIN. Commercial formalin is a solution containing 40% 

 formaldehyde gas in water. "5% solution of formalin" means five parts of 

 commercial formalin to 95 parts of water, this strength containing 2% 

 formaldehyde. For diluting: 



25% formalin =10% formaldehyde = 1 part commercial formalin to 



3 parts water by volume. 

 12-^% formalin = 5% formaldehyde = 1 part commercial formalin to 



7 parts water by volume. 

 10% formalin = 4% formaldehyde = 1 part commercial formalin to 



9 parts water by volume. 

 5 % formalin = 2 % formaldehyde = 1 part commercial formalin to 



19 parts water by volume. 

 2^% formalin = 1% formaldehyde = 1 part commercial formalin to 

 39 parts water by volume. 



FORMALIN AND SALT SOLUTION. 5% formalin solution with 

 two tablespoonsful of common salt added to each quart of the solution to 

 reduce the hardening action of formalin on the tissues. 



KAISERLING NO. 1 SOLUTION. 



Commercial Formalin (40 % formaldehyde) 400 cc. 



Potassium Acetate 42-5 gms. 



Potassium Nitrate 22-5 gms. 



Water 1,600 cc. 

 This will make up about two litres of the solution. In preparing the 

 solution the potassium acetate and potassium nitrate, which are in the form 

 of crystalline powders, should be mixed with a little of the water, warmed 

 until they dissolve, before being added to the main solution. 



GLYCERINE SOLUTION. The 75% glycerine solution consists of 

 three parts of glycerine to one part water. 



NAPHTHALENE AND PARADICHLORBENZENE. These are both 

 insect deterrents, obtainable as solids that volatilise slowly. Naphth- 

 alene can be bought as solid lumps (including moth balls) or fine flakes of 

 varying size; and Paradichlorbenzene as solid blocks (sold as "air freshener") 

 or as crystals. When not in use they should be kept wrapped and sealed or 

 in an airtight box. 



