300 Scientific Intellagence. 
The analysis gave the following results ae ees acid (SO,) 
57°58, calcic oxide (CaO) 40°40, ferric oxide (Fe,O,) é Se silicic 
acid (Si 2) 0°05, organic substance and water 1-00==99 
7°58 parts of sulphuric acid require, by theory, 40° 306 parts of 
calcic oxide to form ecalcic, gt A ape latter number corres- 
ponds perfectly with the one fou n say, hence, that the 
incrustation is composed of: Geleie pick 97°89, ferric hydrate 
0°72, silica 0°05, organic matter 0-8 
To my knowledge there has not been described, so far, a boiler 
incrustation which is so very near chemically pure calcic c sulphate, 
and none in which this is so perfectly anhydrous. We know that 
calcic sulphate occurs in nature in two form n one it is com- 
bined with two equivalents of water, viz: ers sulphate 79°07, 
water 20°93, crys ane in ie e thombie prisms, and is called 
Ww 
above the boilin ng point of water, and can n be rendered snhy dues 
until i abe amount of Gracipitite had formed. This pre ope : 
~~ consisted of minute scales with a marked silky luster. Un 
magnifying power of 60 diameters the scales proved to possess 
the aig coh citgtn ey tabular forms of gypsum with the oblique base. 
re perfectly transparent, and “_—_ were twins, - 
precipitate was found on the glass after removing ae bos e from 
Th 
washed, then dried over a uric acid. After ignition a was 
aking into consideration that ngs Be “ 
