40 CALIFORNIA ACADEMY OF SCIENCES. 



slightest current flowing through the apparatus, pass over into 

 the chloride of calcium tubes and ruin the estimation, unless 

 special precautions have been taken to prevent this occurrence. 

 I have found it effectual to insert two plugs of recently ignited 

 asbestos fibre to a distance of about one-fourth the length of the 

 ignition tube; one at each end, thus confining the mineral in 

 the middle portion of the tube, where it may be heated to a 

 bright red without any risk of charring the corks. The plugs 

 serve as perfect strainers of all the suspended dust, and do not 

 impede the current. 



Two independent experiments gave me the following results 

 from one gram: 



Weight of the Ca CI., tubes after j 

 absorption of the water ) 



Weight before absorption 



Water .218'-' .218 5 



The total combined water is therefore somewhat above 21 T \%. 



ESTIMATION OF THE LIME. 



One gram of the powdered mineral was dissolved in dilute 

 muriatic acid, c. p. — solution of oxalate of ammonia (free from 

 residue) added, and ammonia to alkaline reaction. The liquid 

 was heated to near boiling and the oxalate added until no 

 further precipitate appeared even on standing for twenty-four 

 hours. The clear liquid was decanted through a Swedish filter 

 of known ash; the precipitate boiled up with successive portions 

 of distilled water, allowed to stand and the clear liquid decanted 

 through the filter, repeatedly. Finally the precipitate was 

 washed into the filter with boiling distilled water and washed 

 thereon until free from soluble matter. The filter and precipi- 

 tate was removed from the funnel and dried in a water bath; 

 the precipitate detached from the filter as thoroughly as pos- 

 sible — the latter ignited by itself and the ash added to the 

 precipitate placed in a dry platinum crucible of known weight 



