70 ANNUAL OF SCIENTIFIC DISCOVERY. 



ranges from $30 to $75 per ounce, no good qualities being procura- 

 ble at a lower rate than $ 30. Indeed, some years ago, very excellent 

 samples are known to have commanded $ 100 an ounce. The same 

 quality, again, which was valued five years ago at $15 and $20 per 

 ounce, now brings $50. As the demand has increased, the quality 

 of the mineral has also grown poorer ; it being now quite difficult to 

 procure good qualities to any large extent, the bulk of lhat imported 

 being at least seven eighths waste. Two factories in this country turn 

 out annually 104,000 gold pens, complete ; or an average of 2,000 per 

 week. To supply customers and the trade, 150,000 pen-cases, gold 

 and silver, are also required annually. In addition to these, about 

 10,000 pencil-cases (without the pen) are called for; these establish- 

 ments largely supplying the trade in all parts of the country, besides 

 satisfying a very extensive retail demand. A large amount of iridium 

 is of course consumed every year for the immense number of pens 

 manufactured, each of which requires a selected ' point,' carefully 

 chosen from the mass imported in bulk. Here occurs the great waste 

 of this material, of which we have before spoken. We have under- 

 stood that an average of two hundred ounces of iridium is used up 

 every year for the gold-pen manufacture, in the different establish- 

 ments of our own country." 



IMPROVEMENT IN LITHOGRAPHY. 



IN Jameson's PMlosophical Journal, for January, we find a descrip- 

 tion of an improved process in lithography, the invention of Messrs. 

 Schenck and Ghemar. of Edinburgh. A grained lithographic stone 

 is a little warmed, then the composition used for rubbing in tint- 

 stones, known to the generality of lithographers, mixed with an addi- 

 tion of white wax and a little copal varnish, is rubbed down with a 

 piece of coarse, short-haired flannel, or coarse cloth, until the color 

 becomes an equal brown gray. After this the drawing is either 

 sketched upon the stone with soft lithographic chalk, or traced in the 

 ordinary way with red paper. The lighter parts may be rubbed lighter 

 in color ; the highest lights are taken out with a scraper, which is 

 also used to blend the finer tints carefully together ; darker paints can 

 be rubbed in darker, and finished with softer or harder lithographic 

 chalks. The darkest parts are laid in with liquid ink, with the brush 

 or pen, after which the stone is strongly prepared with acid, and thus 

 in a short time a very powerful design can be produced. Drawings 

 executed in this manner are easily printed, and stand many impres- 

 sions. The merit of this process consists in taking advantage of the 

 chemical composition of the stone and the chemical nature of its print- 

 ing, and the discoverers say that in numerous trials they have been 

 able to produce u almost instantly the middle tints of any surface and 

 which do print,"' a result which in every other mode of printing re- 

 quires much time. The cause of the reproach often made against 

 lithography, of its gray tone and want of color, is thus removed, and it 

 may now safely be averred that great power, depth, and brilliancy of 

 tone, together with a variety of texture, c:ni be attained with great 



