Imitation Manilla Pulp from Wood.—Mr. George E. Marshall, of Turner's Falls, Mass., patented a process some years back by which wood, under the action of hot water, and under a heavy pressure, acquires the characteristic colour of manilla. The wood, having been cut as usual, is placed in a closed vessel or tank capable of resisting high pressure, if necessary, of 450 lbs. to the square inch, the material being closely packed. At the bottom of this tank is an opening with a valve, through which the water, previously heated to a point above boiling, and below 280°, is forced by a hydraulic press to such an extent as to saturate and to completely permeate the wood, and to soften and drive out of the pores the gum, resins, and acids; and if the temperature is kept sufficiently hot, it gives the pulp the desired colour belonging to a finely-made manilla paper. This may be aided somewhat by the introduction of a small quantity of some alkaline substance to act on the acids. The water may be heated in a coil outside, and forced into the tank by a hydraulic press. The water thus heated and forced in leaves the wood or the pulp in the most desirable condition for work and for colour. Pulp made from wood treated below the boiling point will be white; but this process is said to secure the desired manilla colour by raising the temperature to 240° or 250° for a light pulp, and as high as 280° for a dark pulp. No pressure is required from the steam above three atmospheres, but the press may give from 450 to 500 lbs. to the square inch, and practice has shown that the greater the pressure the more speedy is the operation on the wood.[36]

Testing Ultramarines.—The sample of ultramarine should be examined as to its power of resisting the action of alum solutions, which may readily be done by the method suggested by Mr. Dunbar:—"Dissolve the same amount of each sample in water, and mix in this water about ½ lb. of pulp. When thoroughly mixed, and each lot of pulp is well and evenly coloured, add one glassful of the ordinary mill alum liquor, either from pure alum, or aluminous cake to each, losing no time over the operation. Stir each well and continuously with a glass rod, and note the glasses carefully as to the length of time each sample keeps its colour." To ascertain the staining power, so called, of the ultramarine, and at the same time the tone, or tint, which it will impart when mixed with pulp, 25 grains of each sample should be mixed with 100 of kaolin or sulphate of lime (pearl hardening) and the several mixtures then worked up into a paste with a little water by means of a spatula, when the differences in the staining power of the respective samples will at once become apparent if either be of inferior quality. To make the test more complete, a like amount of commercially pure ultramarine should be mixed with 100 grains of kaolin for the purpose of comparison. In this way a ready judgment may be formed as to the quality of the sample under examination.

Strength of Paper.—The comparative strength of samples of paper may he determined by cutting strips an inch in width from each sample, and suspending these from a rigid iron bar. Weights are then cautiously attached to each until the sample breaks, when the difference in the weights sustained by the respective samples before the breaking point is reached will determine the comparative strength of the samples tested. Mr. Parkinson, of St. George's Road, Preston, furnishes a simple contrivance for determining the breaking points of paper, and so comparing their value.

[TABLES.]

I.—Dalton's Table showing the Proportion of Dry Soda in Leys of different Densities.

SpecificDry SodaBoilingSpecificDry SodaBoiling
gravity ofper cent.points.gravity ofper cent.points.
solution.by weight.solution.by weight.
1·8563·6600°1·3626·0235°
1·7253·8400°1·3223·0228°
1·6346·6300°1·2919·0224°
1·5641·2280°1·2316·0220°
1·5036·8265°1·1813·0217°
1·4734·0255°1·129·0214°
1·4431·0248°1·064·7213°
1·4029·0242°

II.—Table of Strength of Caustic Soda Solutions at 59° F. = 150° C. (Tünnerman).

Specific GravityDegreesPer cent. ofEquivalent per cent.
(Water 1,000).Twaddell.Soda.of 60 per cent.
Caustic Soda.
1·00400·800·3020·503
1·00811·620·6011·001
1·01633·261·2092·015
1·02464·921·8133·021
1·03306·602·4184·030
1·04148·283·0225·037
1·050010·003·6266·043
1·058711·744·2317·051
1·067513·504·8358·059
1·076415·285·4409·067
1·085517·106·04410·073
1·094818·966·64811·080
1·104220·847·25312·090
1·113722·747·85713·095
1·123324·668·46214·103
1·133026·609·06615·110
1·142828·569·67016·117
1·152830·5610·27517·125
1·163032·6010·87918·131
1·173434·6811·48419·140
1·184136·8212·08820·147
1·194838·9612·69221·153
1·205841·1613·29722·161
1·217843·5613·90123·170
1·228045·6014·50624·177
1·239247·8415·11025·170