164 Compofitlon of the Stvedi/Jj Stone Taper. 



black and friable like the preceding. A fpecimen of the 

 eighth burnt for two minutes, and then continued black 

 and fufliciently hard. The fame was the cafe almoft with 

 the ninth fpecimen. A fpecimen of the tenth, though it 

 became black, was however fcarcely changed. A fragment 

 of the eleventh experiment burnt with a flame for about two 

 minutes, and was converted into aflies ; which was the cafe 

 alfo with the fpec men produced by the twelfth experi- 

 ment. 



Thofe fpecimens produced by my fourth, fixth, feventlr, 

 eighth and ninth experiments, feemed to be the beft in their 

 external qualities and their power of withftanding fire and 

 water. The fame fragments fuffered as little from the in- 

 fluence of the weather and atmofphere as the Swediih. The 

 materials for making this article may be readily procured 

 for a fmall price ; and the procefs is Ample, and requires 

 very little time. My fpecimens indeed were not fo neat and 

 eleo-ant as the Swediih; but this inferiority may be obviated 

 by practice and experience : and even in its imperfect ftate 

 the invention may be of great economical utility. 



The cement which the Swedes recommend for filling up 

 the interftices between the fquares, and of which I received 

 a fpecimen from Mr. Cameron, was compofed of linfeed 

 oil varniih, white lead and chalk, mixed together in fuch a 

 manner as to approach to a fluid ftate, that it might more 

 eafily infinuate itfelf into the fliTures. 



As the chief ufc of this invention is to cover and ineruft 

 lioufes, I was defirous of trying my production by cxpofing 

 it to the effects of the weather. I therefore nailed frag- 

 ments of the Swediih ftone paper, and of that made by 

 myfclf, to a fmall board ; and having daubed over the join- 

 ings with cement, I expofed them in the month of Auguft 

 on the top of my houfe, and in the beginning of April thjj 

 *ext year I found they had undergone no change. 



IX. On 



