ECONOMICAL MATERIALS. 419 



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The grey Ircnton limestone forms a fine materia! for building. The new Catholic cathedra 

 at Montreal is built of lliis variety of the trenton. It resembles granite, and being equally 

 durable, and much more easily wrought, ought to be preferred when it can be procured. 



Substances for clarifying syi'ups, tuater, etc. Slate for roofing does not occur in the Second 

 district ; but a variety suitable for (lagging may be obtained south of Essex, on the lake in 

 Essex county. This rock is used in France for clarifying sugar, syrups, etc. It appears that 

 it is the bituminous variety ; and that in order to be employed, it should be liurnt and then 

 pulverized, when it is ready for use. Tlie bituminous slate, it will bo recollected, occurs at 

 numerous places ; and as it is nseiul for the purpose specified, may it not also be used for 

 purifying rain water for cisterns ? The decomposing slates of Loraine and Rodman may open 

 a new field of industry to some of the inhabitants in the manufacture of alum. 



Hydraulic lime. Limestone for hydraulic purposes is abundant in the calciferous sandrock. 

 Some variety of opinion is expressed in relation to its qualities, which probably arises from 

 liie want of care in selecting the strata intended for burning. 



Fire-stones. Rocks which will sustain a high heat without melting, cracking or exfoliating, 

 are termed fii'e-stoncs. Of these rocks we have three : the Potsdam sandstone, the Rensse- 

 laerite and Steatite. The first borders the district on three sides almost continuously ; but 

 from this extended mass it is necessary to select those strata which arc free from feldspar. 

 This kind is used commonly in the northern counties for the hearths of furnaces ; and when 

 the composition is right, that is, when composed of siliceous grains and uncrystallized in the 

 mass, it is one of the best of fire-stones. Rensselaerite may be employed as a lining for 

 stoves, and for all the smaller purposes which may require a substitute for steatite. I placed 

 a small slab of it in the midst of ignited anthracite, where it remained several hours with- 

 out suffering any change except becoming whiter and harder. Steatite is also found in Fowler, 

 but it is not abundant in the northern district. 



Sand for glass. The great abundance of the potsdam sandstone removes the necessity of 

 employing sand, although this exists at several places. Wherever it is found, however, it is 

 derived from the potsdam. The material, either in the rock or in a state of sand, is in the 

 greatest abundance. 



Sand for sawing, polishing, and sand-paper. The same material, as stated above, may be 

 employed for either of those specified purposes. The rock therefore is one of the greatest 

 importance, as we see when we enumerate the specific objects for which it may be employed. 



Glazing materials. The tertiary clay of Lake Champlain forms one of the finest materials 

 for glazing common earthen ware. To glaze the articles, it is only necessary to dip them 

 into a solution or mixture of the clay with water, of about the consistence of cream. Tlie 

 color will depend upon the subsequent burning. It is easy to show why this material may- 

 be thus used : the alumina is mixed with a quantity of carbonate of lime, which operates as a 

 flux to the aluminous part. Glazing of a finer kind is found in the feldspars of Chester in 

 Warren county, and in Gouverneur in St. Lawrence county, and several towns in the vicinity. 

 The porcelain clay of Johnsburgh probably contains colored strata which may be employed 

 for some purposes in pottery, either in glazing or forming the body of the ware. 



