PiiOCEEDINGS OF TEE POLYTECHNIC ASSOCIATION. 1063 



Mr. T. D, Stetson inquired if large masses of tliis stone could be 

 made as well as the specimens. 



Mr. Ilodgeson replied tliat large masses could be made equally as 

 well. If the stone is exposed to a dull red heat it improves it. 



Mr. Stetson wanted to know how long it is requisite to keep the 

 stone in the oxalic acid bath. 



Mr. Ilodgeson said the time varied, according to size, from two to 

 four hours. 



llr. J. Johnson inquired how much acid a cubic foot of the stone 

 Vv'<.)uld absorb. 



Mr. Ilodgeson said he had not experimented on a scale large 

 enough to answer that question. The oxalic acid in a weak solution, 

 four ounces to a gallon of water ; the proportion of moistened lime is 

 from three to four, according to the quality of the sand ; slightly 

 slaked quicklime is used. 



Mr. D. Blanchard inquired at what price this stone could be made 

 for decorative purposes ? 



Mr. Ilodgeson replied that they could be made at a fraction over 

 the price of ordinary architectural ornaments, say some hfteen per 

 cent. 



Dr. P. 11. Yanderweyde said it was a happy idea to employ the 

 oxalate of lime in this process. Now, in order to make the lime 

 insoluble, oxalic acid is put in it. The principle is simple. The 

 lime in the sand has great affinity for the oxalic acid with which it 

 combines and becomes the oxalate of lime, which is insoluble in 

 water. In regard to the amount of oxalic acid absorbed, all that is 

 required is to make the combination complete. 



A Xew Motor. 



Mr. John Johnson exhibited a model of a motor, which was placed 

 in a glass vessel in which water is boiling. The flame of gas being 

 placed to one side of the vessel, an upward current of steam is gene- 

 rated on one side, which acts on the paddles of a wheel wholly 

 immersed in the water, causing the wheel to revolve quite regularly. 

 It might, he said, be called a household motor. The velocity of the 

 paddles are due to the amount of water evaporated. It performs as 

 well as any rotary engine. 



The eh.airman next called upon Mr. Frank Dibbin, a former mem- 

 ber of the Polytechnic, whom he noticed to be present, and who had 

 just returned fr-om Cok>vi\do,-to make some remarks: " 



