162 



THE ESTIMATION OF SUGARS. 



as possible by the pump. It is then detached from the filter 

 pump, and connected with a hydrogen apparatus, being clamped 

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

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

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

 tube is dry ; it is allowed to cool while the hydrogen is passed 

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

 amount of copper reduced. Table XXIX. 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 33 t 4 ^ = 250-9. 



ooo 



By taking a weight of milk-sugar as nearly as 

 possible equal to that in the solution, and estimating 

 the copper reduced by this, the calculation can be 

 made in a similar manner from the weight of copper 

 obtained. 



The cuprous oxide may be reduced in a Gooch 



T^ lg 'Jf\ crucible by placing it in a muffle, and passing in 

 Filter lube. , J . f , & 



a current oi hydrogen. 



TABLE XXIX. FOR CALCULATING THE AMOUNT OF 



MlLK-SuGAR FROM THE QUANTITIES OF COPPER REDUCED. 

 This Table is due to Wein. 





