PROCEEDINGS OF SECTION H. 347 
break up clotted particles of cement with a glass rod. Add 
20 cm.® water and filter, retaining undissolved portions in 
the beaker, to these add 5 em.* hydrochloric acid and a few 
drops of nitric acid, heat for a few moments, add 10 cm.* 
water, filter and wash, dry ‘and ignite the filter—Insoluble in 
acid. . 
2. Evaporate the filtrate from the above to dryness, heating 
finally to 150 deg. C., add 10 cm.* hydrochloric acid, a few 
drops of nitric acid, and warm for about ten minutes. Add 
20 cm.* water, filter and wash. 
3. Dry and ignite the filter, fuse in platinum crucible with 
carbonate of soda (silica free), boil out with water, add excess of 
hydrochloric acid and evaporate to dryness, heating to 105 
deg. C. Take up with hydrochloric acid, dilute with water, 
filter and wash. Dry and ignite filter—Soluble Silica. Add 
excess of ammonia to the filtrate, boil and filter. Dry and 
ignite the filter—Alumina. 
4. Add excess of ammonia to the filtrate and washings from 
2, heat for a few minutes, filter, decanting as closely as pos- 
sible from the precipitated iron oxide and alumina, redissolve 
the precipitate with hydrochloric acid, add about 50 cm.? 
water, then excess of ammonia, warm and filter. Dry and 
ignite filter—Oxide of Iron and Alumina. 
5. The filtrate from 4 is raised to boiling point, and oxalate 
of ammonia added in excess, continue the boiling, stirring mean- 
while, for one or two minutes, cool, add 10 cm.? ammonia, 
stir well, and set aside for six hours, filter, wash with dilute 
ammonia solution, dry, ignite over blast to constant weight—= 
Lime. 
The filtrate from 5 is concentrated by evaporation, and 
the magnesia precipitated as ammonium-magnesium phosphate, 
setting aside for ten hours, filter, dry, and ignite over blast 
—= Magnesia. 
The specific gravity determined on 50 grammes, using kero- 
sene or turpentine. 
MECHANICAL TEstTs. 
The briquettes were all made and tested by one person; 
the cement was mixed with as little water as possible, generally 
18 per cent. to 20 per cent. being used, enough being mixed at 
once on a slate to allow of three briquettes of 1 square inch 
section to be made, according to temperature. 
They were hand rammed with a small iron, having a head of 
1 x 3, and trowelled off smooth. 
The briquettes were broken in a Faija testing machine, con- 
trolled by an Adie machine. 
