LARD AND LARD ADULTERATIONS. 



429 



into the open neck of the flask. If the bath is to be kept at the boiling 

 temperature the flask should be held steady by a wire attached to 

 the edges of the vessel or by some other means. If the specific grav- 

 ity is to be taken at a lower temperature than boiling water, say 40, 

 the flask having been filled with distilled water at a temperature be- 

 low 40, as described above, is closed with the stopper carrying the ther- 

 mometer, which is pressed firmly to its place, care being taken that no 

 air bubbles are occluded. The temperature of the bath is then raised 

 slowly until it reaches 40 to 41. The temperature of the bath is taken 

 with another thermometer. The thermometer of the flask is carefully 

 watched, especially as it approaches the required point. When the 



FIG. 17. 



temperature of the bath is only slightly above that required the final 

 temperature is reached only after some time, usually about one-half 

 hour. The moment the required temperature is reached any water on 

 top of the capillary tube is removed with blotting paper, the cap is 

 placed upon the capillary tube and the picuometer taken from the bath; 

 it is at once wiped perfectly dry and placed in the balance, where it is 

 allowed to remain until the temperature indicated by the thermometer 

 is sensibly that of the balance room ; it is then weighed and the weight 

 of distilled water which it contains at that temperature determined. 

 When the determination is to be made at the temperature of boiling 

 water the specific- gravity flask is secured in the bath as indicated and 



