118 University Geological Survey of Kansas. 
during the past four years. Patent number 549,151, filed Decem- 
ber, 1894, by Mr. Geo. W. Parker, formerly of San Francisco, is 
entitled ‘‘ Process of Treating Gypsum Rock to Imitate Chal- 
cedony.’’? The claim is as follows: 
‘¢The process of treating gypsum rock to represent chalcedony consists in first 
completely dehydrating the rock by the action of hot air, next allowing the now 
porous rock to absorb a solution of sulphate of iron, nitric acid and potassium 
sulpho-cyanide, after which immersing in a solution of aluminum sulphate 
[Al,(SO,),] for fifteen hours, next expose to air and then polish as set forth.”’ 
Patent number 588,287, of August, 1897, by Geo. W. Parker, 
of Grand Rapids, Michigan, (filed October 18, 1895; renewed 
July 10, 1897) is entitled ‘ ae Rock to Imitate Marble.”’ 
The claim is: 
‘‘The process of treating gypsum rock which consists in eliminating the 
moisture from the rock by the action of hot air, then removing the then hot 
calcium sulphate into a closed compartment.charged with the fumes of ammonia 
and then immediately immersing the cool rock in a warm solution of aluminum 
sulphate until the pores are filled, as set forth.” 
Hardened gypsum treated with stearic acid or with paraffine, 
and polished, resembles meerschaum, and it is used for cheap 
pipes. Sometimes a coloring solution of gamboge is added to 
complete the resemblance.* Wagner also records that Fissot 
made artificial stone from gypsum by burning and immersion 
in water first for a half minute, after which it was exposed to 
the air and then again immersed for two or three minutes, 
when the block appeared as hardened stone. 
Uses of Gypsum. 
Gypsum in its ground, uncalcined state is used as land plas- 
ter for fertilizer. Its value in this connection is much disputed 
and unsettled, and the subject will be discussed in the next chap- 
ter. In many states a large portion of the gypsum is thus used ; 
but in this state only 560 tons out of nearly 65,000 tons in 1894 
were ground into land plaster, and still less since that time. 
Land plaster, on account of its absorptive properties, is valu- 
able around houses and stables as a disinfectant. It readily 
takes up the offensive odors, and should be used much more 
than it is, around barns. ‘The plaster absorbs especially the 
43. Wagner, Chemical Technology, p. 333, 1889. 
