GRIMSLEY. | Technology of Gypsum. (da 
@, it is not conclusive to say that the retarder used with the 
rock or any impurities in the gypsum earth were at fault. The 
conditions of calcining and the conditions of mixing and work- 
ing by the plasterer must also be investigated. 
Inexperienced calciners who depend wholly on a thermometer 
plunged at times into the kettle may make a very poor plaster 
from the very best materials. The Kansas calciners seem to 
understand their business, and we have in this state men who 
cannot be surpassed for this work. It is interesting to note in 
this connection that Kansas plasters stand in great favor in the 
east, even where they come under the disadvantage of lower 
freight-rates from mills located nearer these markets. 
The gypsum cement plasters are displacing the old lime plas- 
ters in all the larger buildings and in many private residences. 
The advantages of such plasters are as follows: Being a good 
non-conductor of heat, the cement plaster is valuable in fire- 
proof buildings. It sets more rapidly and dries out much more 
rapidly than lime plaster, so that carpenters can follow the 
plasterers very soon after the plaster is placed on the walls, as 
can also the painters and paper hangers. Coloring matter can 
be mixed with the material in its preparation for mortar to 
produce any tint desired, as the gypsum plaster does not affect | 
coloring matter as lime plaster does. The cement plaster re- 
quires less mortar than other plasters, and ceilings and walls 
thoroughly soaked from leaking and unprotected roofs have not 
been injured. It attains a high polish, and is used for wain- 
scoting as a substitute for marble. Changes of temperature do 
not affect the walls, and therefore they do not chip or crack. 
The walls become dense and hard, and are vermin proof, so 
that the plaster is valuable for hospital walls. 
The great objection to the use of cement plaster has been the 
greater expense. It.costs about one-fourth more than ordinary 
lime plasters, but the results are so much better that it is bound 
to displace them more and more as its advantages become rec- 
ognized. 
Large amounts of cement plaster are used in the fire-proof 
buildings of our large cities. The Marquette building in Chicago 
ing 
