250 ANNUAL OF SCIENTIFIC DISCOVERY. 



vided into equal spaces) such as is usually in the estimation of the value of 

 alkalies, what number of such graduated spaces filled with acid are necessary 

 for the neutralization of a known proportion of the total amount of size-solu- 

 tion as required for the paper in any particular engine, in accordance with 

 the special variety of paper being manufactured. The point of saturation is 

 ascertained by stirring well the size-solution on each successive addition of 

 the acidulous solution, and until the size-solution so treated slightly reddens 

 litmus paper. The quantity of acid solution being thus determined for a 

 known proportion of the size-solution, it is easy to ascertain by calculation the 

 requisite amount for the whole of the size-solution to be decomposed. But a 

 more convenient system for practical purposes is, to have a series of measures 

 capable of containing the requisite amounts of the acidulous solution to neu- 

 tralize the alkali present in one, two, three, or other number of gallons of the 

 size-solution, so that the treatment is then reduced to an exceedingly simple 

 form. In the practical manufacture of paper the following order or sequence 

 of the applied substances, or treatment, is found to be the best, although the 

 order may be varied more or less : The paper pulp being introduced in the 

 sizing-engine, with the customary quantity of water, the necessary or determined 

 quantity of size-solution is added, and at an interval of 20 minutes, more or 

 less, and when the neutralization is complete, and the deposition of the resin 

 thus economically accomplished, any alum which is to be applied, is added. 

 This substance, for ordinary printing papers, is commonly added in the 

 proportion of about two pounds' weight to each hundred weight of the pulp 

 necessary for the manufacture of paper. The proportion varies, however, ac- 

 cording to the required hardness of the surface of the paper, this hardening 

 effect being the chief result due to the introduction of alum in the improved 

 process. In some kinds of paper, alum may be entirely dispensed with in 

 working out this process. This dispensing with alum applies more particu- 

 larly to papers used by lithographers and engravers, for whose work alum is 

 known to be prejudicial. After the addition of the materials to the pulp has 

 taken place in the hereinbefore described order, the usual coloring matter is 

 applied, and at this stage also, any fire-clay, or any other material, with which 

 it may be desired to impregnate the paper. Practical Mechanics 1 Journal. 



IMPROVEMENTS IN TANNING LEATHER. 



Wniti'ds Tn,:ii:i"j Compound. The claims of a patent recently issued to 0. 

 B. Wattles, of Yraddington, N. H., is as follows: 



First, I claim the employment or use of soap combined with salt and lime, 

 for unhairing or depilating the hides. Second, I claim the employment or use 

 of soap combin d with the tan liquor for tanning the hides, substantially as 

 described. 



The above process consists in the use of the ingredients specified in the 

 claim for the purpose of softening the hide, improving its quality, and pre- 

 venting the injurious effects which have hitherto resulted from the use of lime 

 in unhairing. Mr. Wattles uses the soap, salt and lime in unhairing. and the 

 soap and ca \ ling liquors in t u ing. ' study of ;: od tanners has 



