98 



ANALYSIS OF MILK. 



in a horizontal position. A gentle current of hydrogen is passed 

 through, and the tube cautiously heated by a small flame till 

 all the cuprous oxide is reduced to metallic copper, and the tube 

 is dry ; it is allowed to cool wtile the hydrogen is passed slowly 

 through, and weighed. The increase of weight gives the amount 

 of copper reduced. Table X. should be used to calculate the 

 amount of hydrated milk-sugar from the copper. 



The table is used as follows : — Look up in the table the 

 weight of copper (expressed in milligrammes) nearest to the 

 weight obtained, and calculate from this, by a proportion sum, 

 the corresponding weight of milk-sugar. 



Thus, if the weight of copper is 334-1 milli- 

 grammes, take the weight of milk-sugar corre- 

 sponding to 335 milligrammes. 



335 = 251-6 .-. 334-1 = 251-6 x %^ = 250-9. 



By taking a weight of milk-sugar as nearly as 

 possible equal to that in the solution, and esti- 

 mating the copper reduced by this, the calculation 

 can be made in a similar manner from this. 



The cuprous oxide may be reduced in a Gooch 

 crucible by placing it in a muffle, and passing in 

 a current of hydrogen. 



Fig. 7. 



Filter Tube fou 



Milk-Sugar. 



TABLE X. — For Calculating the Amount of Milk-Sugar 



FROM THE Quantities of Coi%"br Reduced. 



This Table is due to Weiu. 



