Hydrometers of Total Immersion. 499 



in water. Using a thread so prepared, the oscillations of the 

 balance are almost as uniform as in the air. P. Chappuis 

 (Adjoint au Bureau International des Poids etMesures) writes: 

 " J'ai fait de nombreuses pesees hydrostatiques dans ces 

 conditions et j'ai pu me convoincre de l'excellence de ce pro- 

 cede qui donne une plus grande precision aux pesees hydro- 

 statiques. " 



The present paper discusses a method of determining 

 specific gravities which may in special cases be more con- 

 venient than the above, and is, I venture to think, quite as 

 accurate. 



Specific gravities are, by this method, determined by 

 hydrometers which, when used, are totally immersed in the 

 liquid. 



Fig. 1. Fig. 2. 



Fig. 1 shows the form used for liquids. By slipping small 

 ring-shaped platinum weights over the stem, the specific 

 gravity of the hydrometer is made to approximate to that of 



