3:22 ANNUAL OF SCIENTIFIC DISCOVERY. 



nurgalls, gives ten pounds of ink, which does not deposit sediment or turn 

 mouldy, and flows readily from the pen. 



CHEMICAL WRITING. 



The following is a copy of the specifications of a patent recently granted 

 to M. Solhausen, for a process for producing chemical marks or writing on 

 paper, without using a liquid like common inks, by employing chemically- 

 prepared paper, and a chemically-prepared pencil, style or other-like instru- 

 ment, to trace, write, or mark on paper, whereby the salts or substances in 

 the pencil and paper, when they come in contact, will chemically unite 

 under hygroscopic conditions at the natural temperature of the atmosphere, 

 and will form visible chemical colored marks or writing on the paper. Hy- 

 groscopic conditions arc necessary to the process to effect chemical writing ; 

 moisture is the agent which enables the salts or substances used to effect 

 chemical union, but no liquid is employed. 



To prepare the paper, the common sizing that is used for writing paper 

 is saturated with a salt or salts, or substances of considerable solubility, and 

 which, when dried with the paper, will maintain its dryncss and freedom 

 from moisture under ordinary atmospheric changes. Colorless salts or sub- 

 stances are preferred for this purpose, or they may be of such a light tint as 

 not to be different from the color of writing paper. This salt or salts, or 

 substance, is to form the ground for the colored marks or writing to be pro- 

 duced on the paper. Various salts may be used for this purpose, according 

 to the color of the marks or writing to be produced. For instance, to pro- 

 duce blue marks or writing, the paper is prepared with ferrocyanidc of am- 

 monium, which is very soluble in water, or with salicylic. To make black 

 marks or writing, indigolic salts, euxanthic salts, and morphine salts are 

 used. To make red marks, meconic salts, kemenic salts, pyromeconic salts, 

 and angelic salts are used. To produce green writing or marks, the paper is 

 prepared with caffeic or themic salts. These salts, cither singly or a mix- 

 ture of those specified for each color, are mixed with the sizing of the paper, 

 which is applied in the usual manner, and the paper is afterwards dried and 

 pressed in the common way. No certain quantity of these salts requires to 

 be described, but about one ounce of any of them is sufficient to impregnate 

 the sizing for about half a ream of common foolscap paper ; a lesser quantity 

 being used to produce feebler colors, and more to produ?c darker shades. 

 Other well-known salts than those specified may also bo used, but those 

 named will effect the results herein described the principal feature of this 

 invention being to produce chemical Writing without an ink. The patentee 

 now takes a deliquescent salt, and, for cheapness, he prefers a ferric oxide 

 the nitrate, chloride, or sulphate of iron, obtained in any of the usual 

 methods. This salt is triturated and mixed intimately with plastic clay, in 

 about the quantities of an ounce of salt to a like quantity, by weight, of clay 

 or similar substance. The ferric clay is then moulded into any desired 

 form to constitute a pencil or tracing instrument, and is afterwards baked in 

 an oven, to drive off the moisture by heat. The heat is continued, at about 



