Chapter 3

From the lathe, the veneer is passed to the cutting table, where it is cut to lengths and widths as desired. It is then conveyed to the second story, where it is placed in large dry rooms, air tight, except as the air reaches them through the proper channels. The veneer is here placed in crates, each piece separate and standing on edge. The hot air is then turned on. This comes from the sheet iron furnace attached to the boiler in the engine room below, and is conveyed through large pipes regulated by dampers for putting on or taking off the heat. There is also a blower attached which keeps the hot air in the dry rooms in constant motion, the air as it cools passing off through an escape pipe in the roof, while the freshly heated air takes its place from below. These rooms are also provided with a net-work of hot air pipes near the floor. The temperature is kept at about 165°, and so rapid is the drying process that in the short space of four hours the green log from the steam box is shaved, cut, dried, packed, and ready for shipment.

After leaving the dry rooms it is assorted, counted, and put up in packages of one hundred each, and tied with cords like lath, when it is ready for shipment. Bird's-eye maple veneer is much more valuable and requires more care than almost any other, and this is packed in cases instead of tied in bundles. The drying process is usually a slow one, and conducted in open sheds simply exposed to the air. Mr. Densmore's invention will revolutionize this process, and already gives his mill a most decided advantage.

The mill will cut about 30,000 feet of veneer in a day, and this cut can be increased to 40,000 if necessary. Mr. Densmore has already received several large orders, and the rapidly increasing demand for this material is likely to give the mill all the work it can do. The timber used is principally curled and bird's-eye maple, beech, birch, cherry, ash, and oak. These all grow in abundance in this vicinity, and the beautifully marked and grained timber of our forests will find fitting places in the ornamental uses these veneers will be put to.

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THE CONSTITUENT PARTS OF LEATHER.

The constituent parts of leather seem to be but little understood. The opinions of those engaged in the manufacture of leather differ widely on this question.

Some think that tannin assimilates itself with the hide and becomes fixed there by reason of a special affinity. Others regard the hide as a chemical combination of gelatine and tannin. We know that the hide contains some matters which are not ineradicable, but only need a slight washing to detach them.

We deem it advisable, in order to examine the hide properly so-called, to dispense with those eradicable substances which may be regarded, to some extent, as not germain to it, and confine our attention to the raw stock, freed from these imperfections.

It is well known that a large number of vegetable substances are employed as tanning agents. Our researches have been directed to leather tanned by means of the most important of these agents.

Many questions present themselves in the course of such an examination. Among others, that most important one, from a practical point of view, of the weight the tanning agent gives to the hide, that is to say, the result in leather of weight given to the raw material. The degree of tannage is also to be considered; the length of time during which the tanning agent is to be left with the hide; in short, the influence upon the leather of the substances used in its production. That is why we have made the completest possible analysis of different leathers.

Besides ordinary oak bark there are used at present very different substances, such as laurel, chestnut, hemlock, quebracho and pine bark, sumac, etc.

Water is an element that exists in all hides, and it is necessary to take it into consideration in the analysis. It is present in perceptible quantity even in dry hides. This water cannot be entirely eradicated without injuring the leather, which will lose in suppleness and appearance. Water should then be considered as one of the elements of leather, but it must be understood that if it exceeds certain limits, say 12 to 14 per cent., it becomes useless and even injurious. Moreover, if there is any excess over the normal quantity, it becomes deceptive and dishonest, as in such a case one sells for hides that which is nothing but water. Supposing that a hide, instead of only 14 per cent., contained 18 per cent. of water, it is evident that in buying 100 pounds of such a hide one would pay for four pounds of water at the rate for which he purchased the hide.

There are, also, some matters soluble in air, which are formed to a large extent from fat arising as much from the hide as from tanning substances. The air dissolves at the same time a certain amount of organic acid and resinous products which the hide has absorbed. After treating with air, alcohol is used, which dissolves principally the coloring matters, tannin which has not become assimilated, bodies analogous to resin, and some extractive substances.

That which remains after these methods have been pursued ought to be regarded as the hide proper, that is to say, as the animal tissue saturated with tannic acid. In this remainder one is able to estimate with close precision that which belongs to the hide. The hide being an elementary tissue of unchangeable form, it is easy, in determining the elementary portion, to find the amount of real hide remaining in the product. With these elements one can arrive at a solution of some of the questions we are discussing.

We give below, according to this method, a table showing the composition of the different leathers exhibited at the Paris Exposition of 1878. They are the results of careful research, and we have based our work upon them:

Matter Soluble Fixed in Air Tannin | | | Matter Solu- | | ble in Alcohol | | | | Moisture | | Gelatine | --+-- --+-- --+-- --+-- --+-- Steer hide, hemlock tanned (heavy leather) 10.95 4.15 19.77 39.1 26.03 Sheepskins, sumac " (Hungarian) 10.8 10.3 12.1 40.3 26.5 Finished calf, pine bark tanned (Hungarian) 11.2 1.7 7.4 41.6 38.1 Steer hide, quebracho tanned (heavy leather) 11.7 1.6 11.2 43.1 32.4 " " chestnut " " " 13.5 0.29 1.99 45.46 38.76 Finished calfskins, oak tanned (Chateau Renault) 12.4 0.33 3.59 46.74 36.94 Steer hide, laurel tanned (heavy leather) 12.4 1.05 7.95 47.47 31.13 " " oak tanned after three years in the vats (heavy leather) 11.45 0.37 3.31 49.85 35.02

The following table shows the amount of leather produced by different tannages of 100 pounds of hides:

Pounds. Hemlock 255.7 Sumac 248.1 Pine 240.3 Quebracho 232 Chestnut 219.9 Oak 213.9 Laurel 210.6 Oak, lasting three years 206

It is important to mention here the large proportion of resinous matter hemlock-tanned leather contains. This resin is a very beautiful red substance, which communicates its peculiar color to the leather.

We should mention here that in these calculations we assume that the hide is in a perfectly dry state, water being a changeable element which does not allow one to arrive at a precise result.

These figures show the enormous differences resulting from diverse methods of tanning. Hemlock, which threatens to flood the markets of Europe, distinguishes itself above all. The high results attributable to the large proportion of resin that the hide assimilates, explain in part the lowness of its price, which renders it so formidable a competitor. One is also surprised at the large return from sumac-tanned hides when it is remembered in how short a time the tanning was accomplished, which, in the present case, only occupied half an hour.

The figures show us that the greatest return is obtained by means of those tanning substances which are richest in resin. In short, hemlock, sumac, and pine, which give the greatest return, are those containing the largest amount of resin. Thus, hemlock bark gives 10.58 per cent. of it, and sumac leaves 22.7 per cent., besides the tannin which they contain. We know also that pine bark is very rich in resin. There is, then, advantage to the tanner, so far as the question of result is concerned, in using these materials. There is, however, another side to the question, as the leather thus surcharged with resin is of inferior quality, generally has a lower commercial value, and is often of a color but little esteemed.

The percentage of tannin absorbed by the different methods of tannages appears in the following table:

Hemlock 64.2 Sumac 61.4 Pine 90.8 Quebracho 75.3 Chestnut 85.2 Oak 76.9 Laurel 64.8 Oak, three years in the vat 70.2

The subjoined is a statement of the gelatine and tannin in leather of different tannages, and also shows the amount of azote or elementary matter contained in each:

Gelatine. Tannin. Azote. Hemlock 60.4 39.6 10.88 Sumac 60.4 39.6 11 Pine bark 52.5 47.5 9.56 Quebracho 57.1 42.9 10.4 Chestnut 53.97 46.03 9.79 Oak 55.87 44.13 10.24 Laurel 60.4 39.6 10.94 Oak, 3 years in vat 58.75 41.25 10.65

It is not pretended that these figures are absolutely correct, as they often vary in certain limits even for similar products. They form, however, a fair basis of calculation.

As to whether leather is a veritable combination, it seems to us that this question should be answered affirmatively. In fact, the resistance of leather properly so-called to neutral dissolvents, argues in favor of this opinion.

Furthermore, the perceptible proportion of tannin remaining absorbed by a like amount of hide is another powerful argument. It remains for us to say here that the differences observable in the quantity of fixed tannin ought to arise chiefly from the different natures of these tannins, which have properties differing as do those of one plant from another, and which really have but one property in common, that of assimilating themselves with animal tissues and rendering them imputrescible.

In conclusion, these researches determine the functions of resinous matters which frequently accompany tannin; they show a very simple method for estimating the results of one's work, as well as the degree of tannage.--_Muntz & Schoen, in La Halle aux Cuirs_.--_Shoe & Leather Reporter_.

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NEW HIGH SCHOOL FOR GIRLS, OXFORD.

The new High School for Girls at Oxford, built by Mr. T.G. Jackson, for the Girls' Public Day School Company, Limited, was opened September 23, 1880, when the school was transferred from the temporary premises it had occupied in St. Giles's. The new building stands in St. Giles's road, East, to the north of Oxford, on land leased from University College, and contains accommodation for about 270 pupils in 11 class-rooms, some of which communicate by sliding doors, besides a residence for the mistress, an office and waiting-room, a room for the teachers, cloak rooms, kitchens, and other necessary offices, and a large hall, 50 ft. by 30 ft., for the general assembling of the school together and for use on speech-days and other public occasions. The principal front faces St. Giles's road, and is shown in the accompanying illustration. The great hall occupies the whole of the upper story of the front building, with the office and cloak-rooms below it, and the principal entrance in the center. The class-rooms are all placed in the rear of the building, to secure quiet, and open on each floor into a corridor surrounding the main staircase which occupies the center of the building. The walls are built of Headington stone in rubble work, with dressings of brick, between which the walling is plastered, and the front is enriched with cornices and pilasters, and a hood over the entrance door, all of terra cotta. The hinder part of the building is kept studiously simple and plain on account of expense. Behind the school is a large playground, which is provided with an asphalt tennis-court, and is picturesquely shaded with apple-trees, the survivors of an old orchard. The builders were Messrs. Symm & Co., of Oxford; and the terra cotta was made by Messrs. Doulton, of Lambeth. Mr. E. Long was clerk of works.--_Building News_.

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PROGRESS IN AMERICAN POTTERY.

No advance in any industry has been more sure than in that of pottery and chinaware, under the American tariff, or more rapid in the past four or five years. It took Europe three centuries and the jealous precautions of royal pottery proprietors to build up the great protectorates that made their distinctive trade-marks of such value. The earlier lusters of the Italian faience were guild privacies or individual secrets, as was almost all the craft of the earlier art-worker. Royal patronage in England was equivalent to a protective tariff for Josiah Wedgwood; and everywhere the importance of guarding the china nurseries has been understood. We have in this country broadcast and in abundance every type of material needed for the finest china ware, and for the finer glasses and enamels. The royal manufactories in Europe were hard put to it sometimes for want of discovering kaolin beds in their dominions, but the resources of the United States in these particulars needed something more than to be brought to light. The manipulation and washing of the clays to render them immediately useful to the potteries depends entirely upon the reliance of these establishments upon home materials. The Missouri potteries have their supplies near home, but these supplies must be put upon the market for other cities in condition to compete with the clays of Europe. There are fine kaolin beds in Chester and Delaware counties in this State; there are clay beds in New Jersey, and the recent needs of Ohio potteries have uncovered fine clay in that State. This shows that not only for the manufacture itself, but for the development of material here, everything depends upon the stimulus that protection gives.

Ohio china and Cincinnati pottery are known all over the country. The Chelsea Works, near Boston, however, are as distinguished for their clays and faience, and for lustrous tiles especially (to be used in household decoration) can rival the rich show that the Doulton ware made at the Centennial. Other New England potteries are eminent for terra cotta and granite wares. On Long Island and in New York city there are porcelain and terra cotta factories of established fame, and the first porcelain work to succeed in home markets was made at the still busy factories of Greenpoint. New Jersey potteries take the broad ground of the useful, first of all, in their manufacture of excellent granite and cream-colored ware for domestic use, but every year turn out more beautiful forms and more artistic work. The Etruria Company especially have succeeded in giving the warm flesh tints to the "Parian" for busts and statuettes, now to be seen in many shop windows. These goods ought always to be labeled and known as American--it adds to their value with any true connoisseur. Some of these establishments, more than others, have the enterprise to experiment in native clays, for which the whole trade owes their acknowledgments.

The demand all through the country by skillful decorators for the pottery forms to work upon, points to still greater extensions in this business of making our own china, and to the employment and good pay of more thousands than are now employed in it. A collection of American china, terra cotta, etc., begun at this time and added to from year to year, will soon be a most interesting cabinet. Both in the eastern and western manufactories ingenious workers are rediscovering and experimenting in pastes and glazes and colors, simply because there is a large demand for all such, and they can be supplied at prices within the reach of most buyers. It needs only to point out this flourishing state of things, through the "let-alone" principle, which protection insures to this industry, to exhibit the threatened damage of the attempt, under cover of earthenware duties, to get a little free trade through at this session.--_Philadelphia Public Ledger_.

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PHOTOGRAPHIC NOTES.

_Mr. Warnerke's New Discovery_.--Very happily for our art, we are at the present moment entering upon a stage of improvement which shows that photography is advancing with vast strides toward a position that has the possibility of a marvelous future. In England, especially, great advances are being made. The recent experiments of our accomplished colleague, Mr. Warnerke, on gelatine rendered insoluble by light, after it has been sensitized by silver bromide and developed by pyrogallic acid, have revealed to us a number of new facts whose valuable results it is impossible at present to foretell. It seems, however, certain that we shall thus be able to accomplish very nearly the same effects as those obtained by bichromatized gelatine, but with the additional advantage of a much greater rapidity in all the operations. In my own experiments with the new process of phototypie, I hit upon the plan of plunging the carbon image, from which all soluble gelatine had been removed, into a bath of pyrogallic acid, in order to still further render impermeable the substance forming the printing surface. I also conceived the idea of afterward saturating this carbon image with a solution of nitrate of silver, and of subsequently treating it with pyrogallic acid, in order to still further render impermeable the substance forming the printing surface. But the process described by Mr. Warnerke is quite different; by means of it we shall be able to fix the image taken in the camera, in the same way as we develop carbon pictures, and afterward to employ them in any manner that may be desirable. Thus the positive process of carbon printing would be modified in such a manner that the mixtures containing the permanent pigment should be sensitized with silver bromide in place of potassium bichromate. In this way impressions could be very rapidly taken of positive proofs, and enlargements made, which might be developed in hot water, just as in the ordinary carbon process, and at least we should have permanent images. Mr. Warnerke's highly interesting experiments will no doubt open the way to many valuable applications, and will realize a marked progress in the art of photography.

_Method for Converting Negatives Directly into Positives_.--Captain Bing, who is employed in the topographic studios of the Ministry of War, has devised a process for the direct conversion of negatives into positives. The idea is not a new one; but several experimenters, and notably the late Thomas Sutton, have pointed out the means of effecting this conversion; it has never, however, so far as I know, been introduced into actual practice, as is now the case. The process which I am about to describe is now worked in the studios of the Topographic Service. The negative image is developed in the ordinary way, but the development is carried much further than if it were to be used as an ordinary negative. After developing and thoroughly washing, the negative is placed on a black cloth with the collodion side downward, and exposed to diffuse light for a time, which varies from a few seconds to two or three minutes, according to the intensity of the plate. Afterward the conversion is effected by moistening the plate afresh, and then plunging it into a bath which is thus composed:

Water 700 cub. cents. Potassium bichromate 30 grams. Pure nitric acid 300 cub. cents.

In a few minutes this solution will dissolve all the reduced silver forming the negative; the negative image is therefore entirely destroyed; but it has served to impress on the sensitive film beneath it a positive image, which is still in a latent condition. It must, therefore, be developed, and to do this, the film is treated with a solution of--

Water 1,000 grams Pyrogallic acid 25 " Citric acid 20 " Alcohol of 36° 50 cub. cents.

The process is carried on exactly as if developing an ordinary negative; but the action of the developer is stopped at the precise moment when the positive has acquired intensity sufficient for the purpose for which it is to be used. Fixing, varnishing, etc., are then carried on the usual way. The great advantage of this process consists in the fact of its rendering positives of much greater delicacy than those that are taken by contact; and, on the other hand, by means of it we are able to avoid two distinct operations, when for certain kinds of work we require positive plates where a negative would be of no service. M. V. Rau, the assistant who has carried out this process under the direction of Captain Bing, has described it in a work which has just been published by M. Gauthier-Villars.

_Experiments of Captain Bing on the Sensitiveness of Coal Oil_.--The same Captain of Engineers has undertaken a series of very interesting experiments on the sensitiveness to light of one or two substances to which bitumen probably owes its sensitiveness, but which, contrary to what takes place with bitumen, are capable of rendering very beautiful half tones, both on polished zinc and on albumenized paper. These sensitive substances are extracted by dissolving marine glue or coal-tar in benzine. By exposure to light, both marine-glue and coal-tar turn of a sepia color, and, in a printing-frame, they render a visible image, which is not the case with bitumen; their solvents are in the order of their energy; chloroform, ether, benzine, turpentine, petroleum spirit, and alcohol. Of these solvents, benzine is the best adapted for reducing the substances to a fluid state, so as to enable them to flow over the zinc. The images obtained, which are permanent, and which are very much like those of the Daguerreotype, are fixed by means of the turpentine and petroleum spirit. They are washed with water, and then carefully dried. It is possible to obtain prints with half-tones in fatty ink by means of plates of zinc coated with marine-glue. Some attempts in this direction were shown to me, which promised very well in this respect. We are, therefore, in the right road, not only for economically producing permanent prints on paper, but also for making zinc plates in which the phototype film of bichromatized gelatine is replaced by a solution of marine-glue and benzine. The substance known in commerce under the name of pitch or coal-tar will produce the same results.