188 ANNUAL OF SCIENTIFIC DISCOVERY. 



tion consists in the employment of iodine or bromine, together with 

 ferrocyanide or ferricyanide of potassium and starch, either in the manu- 

 facture or preparation of safety paper. For this purpose, iodine or 

 bromine is used in any of their ordinary combinations with bases ; but 

 iodine, being the cheaper material, is preferred to any com pound of bro- 

 mine. Of the compounds of iodine, the patentee employs in preference 

 that known as iodide of potassium, such substance being most readily 

 attainable in the market, and in no degree affecting the color of the 

 paper. The mode of applying this substance is, by mixing it with the 

 pulp or size, or the paper may be saturated with a solution of the me- 

 tallic iodide. The ferrocyanide of potassium is mixed with the size, or 

 it may be applied subsequently to the sizing, as in the case of the 

 metallic iodide. The starch is preferred to be mixed with the pulp in 

 the engine ; but it may, like the other chemical ingredients, be used 

 in an after stage of the process. The proportions for these several ma- 

 terials, used for rendering paper sensitive to the action of reagents, are 

 by no means absolute ; but, as a guide, it may be stated, that the fol- 

 lowing have been found to answer the purpose ; viz., for a ream of post, 

 weighing about 18 pounds, one ounce iodide of potassium, quarter ounce 

 ferrocyanide of potassium, one pound starch. On the application to 

 paper, prepared as above set forth, of reagents, to dissolve out or absorb 

 any ink markings therefrom, the tendency will be to break up one of 

 the salts named. Thus, on the application of chlorine or mineral acids, 

 the iodine will be liberated, and, combining with the starch, will form 

 an insoluble iodide of starch, of a dark color ; and, further, the iron, 

 which ink generally contains, being attempted to be dissolved by either 

 vegetable or mineral acids, the ferrocyanide of potassium will combine 

 with it in solution and form the well-known Prussian-blue compound, 

 which will become diffused over the adjacent portion of the paper. 

 Chemical Gazette. 



CLAUSSEN'S IMPROVEMENTS IN THE MANUFACTURE OF FLAX. 



AT the close of the year 1850, it was announced that M. Claussen, 

 of London, had discovered a process, whereby the harsh and elastic 

 fibres of the flax-plant might be converted into a soft down-like sub- 

 stance, analogous to the fibres of cotton, and capable of being treated 

 in its after stages, in every respect, similar to it. The various pro- 

 cesses by which this is effected appear to be somewhat as follows : In 

 the first stage, the stem of the flax-plant is, to a considerable extent, 

 freed from its straw, leaving the fibre in a partially cleaned state. 

 This is effected by a machine. Hitherto, the great difficulty with all 

 growers of flax has been the preparation of the crop for market ; the 

 grower having been compelled either to resort to the tedious and pre- 

 carious process of steeping his flax, or to dispose of it to factors as it 

 came from the field, upon any terms which they might think proper to 

 offer. This machine will enable the producer, without resort to any 

 steeping process, to reduce the bulk of his flax, and, at the same time, 

 admit of his returning to the soil, in the shape of the straw removed* 

 a large portion of the nutritive matter extracted, and which, formerly 



