cclxxiv GENERAL SUMMARY OF SCIENTIFIC AND 



fibre), and a number of processes have been devised for util- 

 izing these facts in the arts. The peculiar compound known 

 as cupro-ammonium appears to be an admirable solvent for 

 cellulose, dissolving it completely without in the least de- 

 stroying its properties. From this solution the cellulose 

 can bo again precipitated in a perfectly pure state by the 

 employment of the proper re-agents. This observation has 

 already been utilized in the manufacture of a number of 

 useful articles from woody fibre, paper stock, seaweed, and 

 the like. It has been employed in making paper impermea* 

 ble to water, the sheets being simply immersed for a few 

 seconds in the metallic solution, then passed between rollers 

 and dried. Paper thus treated becomes quite impermeable 

 and leathery, resisting even the disintegrating action of 

 boiling water. By passing a number of sheets together 

 through the rollers, an extremely thick and tough fibre is 

 produced, which forms an excellent substitute for leather, 

 and for which doubtless a great variety of uses will be 

 found. The cupro-ammonium treatment of' paper has al- 

 ready been successfully applied to the production of roofing, 

 gas and water pipes, hats, boats, clothing, etc. 



Other processes for the treatment of paper have been de- 

 vised, and of late to some extent utilized in the arts. The 

 well-known paper-parchment, which has only of late years 

 come to be properly valued, is prepared, as was discovered 

 by Hoffman, by passing unsized paper through strong sul- 

 phuric acid. By this simple treatment it is converted into 

 a substance closely resembling parchment in its appearance 

 and behavior, being not only remarkably strong, but also 

 quite impervious to water, hot and cold. A number of me- 

 tallic salts, of which we may mention chloride of zinc and 

 chloride of aluminum or tin, also act powerfully upon cellu- 

 lose. Paper passed through a solution of either of these 

 substances is affected in the same manner, and perhaps quite 

 as decidedly, as when treated with cupro-ammonium ; and 

 of the article thus prepared quite a variety of applications 

 has been made. When freshly prepared, this article can be 

 pressed into moulds, and made to assume any desired form 

 by this and other means. There have been made combs, 

 knife, fork, and brush handles, gas and Mater conductors, 

 and a great variety of articles of utility or ornament. Even 



