94 DAIRY ANALYSIS 



N 



. Dilute 25 c.c. of the 50 per cent, solution to I litre. 



Check the strength by titration (see below). 



N 



. Dilute 5 c.c. of the 50 per cent, solution to i litre. 



Check the strength by titration. 



Sodium Hypobromite Solution. Add i c.c. of t bro- 

 mine to 10 c.c. of soda solution (for Kjeldahl process). 



Strontia Solution. Dissolve 28-30 grammes of 

 strontium hydrate in 2 litres of water. Treat as baryta 

 solution (p. 92). 



Sulphuric Acid. For Gerber Process. Should con- 

 tain 90-91 per cent. H 2 S0 4 . Acid of specific gravity 

 1.820 to 1.825 fulfils this requirement. 



For Reichert Process. Dilute 25 c.c. strong sulphuric 

 acid to i litre of water ; 2 c.c. of 50 per cent, soda solu- 

 tion should neutralise about 35 c.c. of this solution ; 

 adjust the strength, if necessary, by adding acid or 

 water. 



. Dilute 3 c.c. of strong sulphuric acid to i litre. 

 Check the strength as for hydrochloric acid (0.2 

 grammes only of the sodium carbonate is weighed for - 



"\T ^ ^ 



acid, and 100 c.c. of : - acid should be required for 



0.53 grammes sodium carbonate). 



Thiosulphate Solution. Dissolve 25 grammes of 

 pure sodium thiosulphate and i gramme of salicylic acid 

 in i litre of water. Allow to stand for a few days and 

 filter. Weigh accurately about 0.25 gramme of iodine 

 in a small stoppered flask, add 2 grammes potassium 

 iodide and 2 c.c. of water, and shake gently till the 

 iodine js dissolved. Dilute with water and transfer to a 

 larger Vessel, and run in the thiosulphate solution from 

 a burette till the yellow colour just disappears. Eepeat 

 this two or three times, and from the mean results cal- 

 culate the weight of iodine equivalent to i c.c. 



Titration. Take two burettes, fill one with the 

 alkaline solution, and the other with hydrochloric acid 



