RICHARDS AND PARKER. — BARIC SULPHATE. 



75 



long time, in order that the precipitate, which separates slowly from 

 strongly acid solutions, might have time to deposit; while the second 

 two were filtered within an hour, with the loss of nearly ten per cent 

 of the precipitate. 



Thus the presence of free hydrochloric acid increases the occlusion 

 to an enormous extent. 



In order to determine the effect of dilution, other circumstances 

 remaining the same, two precipitations were made from solutions like 

 those of Series II., diluted fourfold with water. 



Series VI. 



Hence, the more dilute the solutions, the less is the occlnsion. 



In all the preceding cases the precipitate was allowed to run down 

 the side of the beaker in an excessively fine stream, with continual 

 stirring. This procedure had been shown in preliminary experiments 

 to be even more efficacious as a means of diminishing occlusion than 

 the addition of the precipitant in definite drops, no matter how slowly. 

 Two experiments, in which the baric chloride was poured in with 

 great rapidity, close the data to be presented. 



Series VII. 



