If, as has been established upoa high authority, the character and quality of the leather are determined by the nature and quality of the tanning material with which the gelatin is combined or, to adopt a more practical idea, if the leather partakes positively of the properties contained in the substances employed, as when mineral or gummy material is combined with tlio tannin, the result will be, not a perfect and insoluble union, as is the case when pure tannin alone is contained in the liquor, but an irregular and uncertain compound of gelatin with the base employed, and leather made thereform is more or less serviceable in exact proportion to the purity of the elements brought together and circumstances under which they are united; hence it becomes a very important object for the manufacturer, to direct his attention at all times towards securing that material containing the largest portion of pure tannin, freed from all extraneous matter, so far as practicable, to enable him not only to make the most durable article, but produce it in the shortest possible time; two objects connected with the leather interest that, it is believed, can be more fully developed than they are at present. During a recent visit to the tanneries, nothing that came under my notice impressed me more forcibly than the necessity of adopting some rules and regulations among the trade, to correct the abuses and negligence that exist in every section, in this department of the business, by which great losses ars sustained, not only by the tanner, but the consumer of his products, in the damage sustained by the bark, mostly it is believed from want of proper attention while in the forest and before it is hauled to the yard. Hence it is assumed that this is the direct and proper position to start from, if we ever expect to reform abuses, and avoid imposition, which, it would appear, judgiig from the condition of the bark that I examined in me re than two hundred yards, have been increasing in a ratio j roportionate to the demand and increase in price. I observed it was a common practice among the trade, to pay nearly full price for all qualities of bark, which ranged from six to eighteen dollars per cord, depending upon locality; and when a reduction was made it was not in proportion to the difference between damaged and sound bark; also discovered that considerable competition existed to obtain a supply of bark, the quality and value of which was doubtful, notwithstanding some of these competitors had, they informed me, a fair supply of good bark on hand, to whom I suggested per haps they might find it more profitable to curtail their operations to meet the supply of good bark on hand, tiian to pay full price for material that had been deprived of fully one-half of its tanning properties. This growing evil is not confined to oak bark, but exists to an equal extent among the hemlock tanners, although it has been asserted that hemlock bark did not become injured by exposure; this assumption it. is confidently affirmed cannot be maintained and for the fol- [ lowing reasons: * First.—Because it is a self-evident proposition that all per-; isliable articles when exposed to the influence of the elements which are known to destroy their virtues, must as an inevit- [ able consequence part with a portion of their virtues just in ' proportion to the extent they are brought in contact with them. Hence we find that bark exposed for a length of time to rain and snow, the latter frequently melting and passing I through the piles left standing in the woods, must yield up no inconsiderable portion of its tanning properties. Those who have not turned their attention to the real difference between a liquor made from first quality and that made from! damaged bark cannot realize the comparative value in actual > tanning material between the two. From a test made some years since, it was discovered that bark which Imd been exposed tor two days to continued warm rains during the month j of July, had yielded up one-fifth of its tannic acid, and conse-' quently required that much more bark, to produce the required strength of liquor; or, in other words, one cord and j one-fifth to accomplish what one cord of good, sound bark j will do. A test was also made with hemlock bark, which; proved that a cord of that bark which had been standing in ! the woods exposed to the weather for two months had parted with nearly one-fourth of its tanning principle, which had been leached out, entirely extinguished through negligence, I by notfbeing properly protected from those elements that are ', known to destroy the tanning properties of all barks used for ! tanning purposes. Nor is this the only loss incurred through j want of some thorough system by which the bark can be im mediately secured, beyond question, from being injured by ex I posure after it is peeled; the labor of handling, hauling, j grinding, and pitching is the same, with twenty-five to fifty ! per cent less material to tan with, also the injurious influence I of the dark moldy color, a general accompaniment of dam-! aged bark upon the stock. In view of these facts we desire j to direct the attention of the manufacturer to these existing, I and we believe, increasing evils, that they may make a move- j ment to correct them, and thereby in some measure avoid the heavy losses now sustained in this department. It appears from information derived from high English i authority that the trade both there and on the Continent un-' derstand fully the importance of securing the bark crop from possibility of damage, by housing it the same day it is tak n off the tree. When we consider the fact that seven millions of cords of bark are peeled annually in this country at a cost of more than thirty millions of dollars, we can more fully realize the importance of the subject under consideration, and approach more closely the actual losses sustained from these causes to the manufacturer and consumer. If we estimate the average loss upon the entire crop at one dollar per cord.which we believe is below, rather than above.the avearge,from enumerated causes it amounts to the startling sum of $7,000,000 annually, to say nothing of the expenses for handling, hauling, etc.; distribute this loss among 4,000 tanneries and we have an average loss for each of nearly $1,800 per year. Now, these are stubborn facts, that stare us glaringly in the face, yet have rarely, if ever, been brought to the serious notice of the fraternity through the medium of our journals,— and why ? Simply because we have few practical members, who will give us the advantages of their experience through that source; consequently the subject has not received that attention that its importance would seem to claim at our hands. In our judgment the price of all bark should be regulated entirely by the actual amount of tanning principle it contains, for in that alone the profits to the tanner consists; and when bark becomes damaged from any cause, its value, like all other merchandise, should be measured accordingly. A difficulty however seems to present itself, in reference to determining the actual value of all damaged bark, and which I will, to some extent, endeavor to remove by suggesting the adoption of a custom in general use among all manufacturers, i. e., keeping on hand samples of all qualities of bark recognized as merchantable. In the investigation of this branch of our subject, it occurs to my mind that, during the peeling season, there should be a sufficient number of hands detailed for the exclusive purpose of looking after the bark after it is peeled; never allowing it to remain exposed longer than one day to the weather if fair, and always have it turned ross side out, and so laid that it will be sure to shed all the rain let it come from whatever quarter it may; during the bark peeling season storms rarely come from a due northern or westerly course, hence you can always let the flesh side face either of those directions without exposing it to damage from that cause. It is well known that most men who peel bark tor sale, pay but little attention to having it well secured, and in many instances I have known them to turn it flesh side out, so that it would curl up nicely and yield more to the vender and less to the tanner when measured. In all regions where competition exists the man who peels bark for sale being fully aware he can sell his bark readily at a large price and for cash, he is not apt to be very particular, either in regard to quality, or the manner in which his bark is packed in the wagon or other conveyance in which it may be brought to market, knowing as a general thing the demand is fully equal to the supply and consequent-j ly meets with ready cash sale; and my experience has satisfied me that it is a matter of economy for the tanner to have the control of the peeling, hauling, and management of the bark in the woods, as thereby he can have it secured in the 1 best possible manner against damage, even if it should cost ! him an extra quarter or fifty cents per cord, which would be a small amount in consideration of the advantages gained. And as a further security against imposition, it occurs to my ! mind that the judgment of the tanner would be much assist- ed by making selections from bark in all conditions, from the very best down to the m st inferior quality; make the best liquor possible from each, then have them analyzed to determine the exact proportion of tannin contained in each quality, and, as a still further assistance in arriving at correct estimates, let the samples be marked so as to indicate the quality and strength of liquor made from each specimen; by adopting this method it is confidently believed the manufacturer would have a more positive and certain guide by which he could always determine much more accurately and satisfactorily to all parties concerned, or pecuniarily interested, the real value of the article offered for sale. This plan would be preferable to any test that might be made through the medium of the Barkometer, for it is known beyond controvetsy, that results indicated by that instrument are not reliable, because it gives the density of the liquid, and not the quantity ' of tannin contained in it; and all liquors vary in density just in proportion to their purity, all things being equal, and while we might approximate towards the relative strength by applying the Barkometer, it is known that the surest and really only reliable test is the one suggested; actual analysis, or the more sluggish but equally certain indicator, the advancement of the stock when placed in conjunction with the liquor; that is to say, when all conditions are comparatively equal, hides thoroughly prepared, application and temperature of liquors favorable, method of leaching such as will guarantee the best quality of liquor, all of which operations have their influence beneficially or otherwise upon the character and progress of the stock. In concluding my remarks upon this branch of our subject, I desire to call the attention of the trade to the fact that while in Europe and England they tan out one pound of best quality of sole leather with four pounds of bark, it requires twelve to thirteen pounds to do the same work in this country; this alone should satisfy every inquiring mind engaged in the production of leather, that we receive a great amount of material in the shape of bark that does not pay for hauling and the other labor put upon, it, or, in other words, is perfectly worthless and obnoxious in connection with their tanning operations, and earnestly invite the attention of the whole fraternity to the careful consideration of this important subject, whereby they may be induced to adopt some regulations by which these losses will be prevented, and millions of dollars saved annually that now perish, yielding no profit to anybody.
This article was originally published with the title "Practical Suggestions on Tanning Leather" in Scientific American 20, 12, 178 (March 1869)