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XXT. Chemical 'Experiments refpecllng different Methods of 

 rendering Taper and the Writing on it Indtjlrutllble by Fire. 

 By Mr. L. BjRUGNATELLl. From Crell's Chemical 

 Annals for 1797. 



F all the fubftances I have tried, liquor of flint is that 

 which, after a feries of experiments, appears to me to be the 

 moft incombuftible, and the moft proper to fecure paper 

 from deftruclion by fire. I dipped the fheet of paper feveral 

 times in the above liquor, frefh made, or, I daubed it feveral 

 times over the whole paper with a hair brufli, and dried it in 

 the fun or in an oven. Paper prepared in this manner loft 

 fome of its foftnefs, became a little rougher than before, and 

 acquired a lixivious cauftic tafte. In other refpeels it was 

 not different from common white paper. When this paper 

 was laid upon glowing coals, it did not burn like common 

 paper, but became red, and was converted to a coal, which 

 however did not fall into afhes like the coal of common 

 paper, fo that it might therefore be confidered as petrified 

 paper. This coal, however, is exceedingly friable; for, 

 when it is taken between the fingers, or preffed together in 

 any manner whatever, it drops to pieces. 



As the chemifts confider incombuftibility as one of the 

 principal characteriftics of faline fubftances, I made experi- 

 ments with different kinds of falts, to try whether they 

 would render paper incombuftible, like this liquid filiceous 

 potafh, which is not a fait, but a combination confifting of 

 two fubftances. 



I took feveral fheets of common white writing-paper, and 

 dipped each of them, in the fame manner as I had proceeded 

 with the above liquor of flint, in a particular fait, and ob- 

 ferved how the different leaves withftood the fire when 

 thrown into it. I fhall here give an account of my obferva- 

 tions as they occurred. 



No. I. Paper dipped in nitrite of lime. — Leaves of paper 



which had been foaked in nitrite of lime diftinguifhed them- 



3 felves 



