OF ARTS AND SCIENCES. 



257 



Analysis of Cdpric Sulphate. — Second Series: Data. 

 Weiffhts reduced to Vacuum Standard. 



Second Series: Results. 



Third Series. 



It is only by gradual approach that very accurate quantitative work 

 may be realized, and the earlier series were absolutely necessary as a 

 training and preparation for the present one. Tliis series had for its 

 object, not only an investigation of the effect of increased refinement, 

 but also a definite proof that the amount of acid present in cupric 

 sulphate was unaffected by the operations involved in the dehydration 

 of the salt. To this end the first sample was not dehydrated at all, the 

 second was heated only to 250°, and the third was exposed to the full 

 heat of 365°, after the addition of sulphuric acid. Since the percent- 

 age of acid found in these samples did not vary beyond a reasonable 

 limit of error, the proof is satisfactory. 



The additional precautions taken in the preparation of the materials 

 have already been mentioned under appropriate heads. Besides these, 



VOL. XXVI. (n. S. XVIII.) 17 



