74 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



Series IV. 



These results prove the necessity of the old rule, which directs that 

 the baric salt should always be added to the sulphate, if any proof of 

 this was needed. 



lu all these experiments a small amount — perhaps the quarter of a 

 cubic centimeter — of strong hydrochloric acid was added to the sul- 

 phuric acid before precipitation. In order to determine if this acid 

 might have had some effect upon the occlusion, four experiments were 

 made in which the amount of this acid was very much increased. In 

 Nos. 12 and 13 about ten cubic centimeters of strong acid were used, and 

 in Nos. 23 and 24 fully twenty. The first two were allowed to stand a 



Series V. 



