MECHANICS AND USEFUL ARTS. 185 



in large quantities in the leaves of New Zealand flax, may be 

 converted into a gum for sealing envelopes, which, when dry, 

 unites the surfaces of paper so thoroughly that no j)rocess of 

 steaming or soaking will j)ermit them to be separated again. 

 For this reason, it is now being used in large quantities in Eng- 

 land, in the preparation of what are called *' safely envelopes." 



Paper from Shavings and Saivdust. — Dr. Matthiessen, a well- 

 known savant, now appears in the character of an inventor and 

 patentee in England of an important improvement. He sn limits 

 wood when in a state of division, such as shavings, sawdust, or 

 disintegrated wood, to what is known as a rotting process, — tliat 

 is to say, the wood in a state of division is steeped either in run- 

 ning or stagnant water, and is allowed to undergo a rotting or 

 fermenting process, by which process certain constituents of the 

 wood will be decompos.ed and removed, and the subsequent 

 treatment of the residual ligneous fibre for the production of pulp 

 or paper will be thereby rendered more economical, and the pro- 

 cess of boiling and bleaching is more easily effected. 



Ineradicable Writing. — A French technical paper, specially de- 

 voted to the art and science of paper manutacture, states that 

 any alterations or falsifications of writings in ordinary ink may 

 be rendered impossible by passing the paper upon which it is in- 

 tended to write through a solution of one milligram (0.01543 

 English grain) of gallic acid in as much pure distilled water as 

 will fill to a moderate depth an ordinar}^ soup-plate. After the 

 paper thus prepared has become thoroughly dry, it may be used 

 as ordinary j^aper for writing, but any attempt made to alter, fal- 

 sify, or change anything written thereon, will be left perfectly 

 visible, and may thus be readily detected. 



How to make Paper Transparent. — Artists, architects, land sur- 

 veyors, and all who have occasion to make use of tracing-paper 

 in their professional duties, will be glad to know that any paper 

 capable of the transfer of a drawing in ordinary ink, pencil, or 

 water-colors, and that even a stout drawing-paper, can be made 

 as transparent as the thin yellowish paper at present used for 

 tracing purposes. The liquid used is benzine. If the paper be 

 damped with pure and fresh-distilled benzine it at once assumes 

 a transparency, and permits of the tracing being made, and of 

 ink or water-colors being used on its surface without any " run- 

 ning." The paperresumes its opacity as the benzine evaporates, 

 and if the drawing is not then completed, the requisite portion of 

 the paper must be again damped with the benzine. The transpar- 

 ent calico, on which indestructible tracings can be made, was a 

 most valuable invention, and this new discovery of the properties 

 of benzine will prove of further service to many branches of the 

 art profession, in allowing the use of stiff paper where formerly 

 only a slight tissue could be used. 



