(2) The process is quicker, since it can be completed in a few hours, according to the nature of hide or skin and result required.

(3) One-tenth of the space necessary for the old method is required. (4) There is very great economy in labour.

(5) The process of liming is completed with one-twentieth the quantity of water.

(6) The natural grease of the hide is not, as in the ordinary liming process, transformed into an insoluble but into a soluble soap which is largely dissolved out, thus preventing the production of greasy leather.

(7) The structures of wool and hair are preserved, and the felting properties of both are materially enriched.

(8) The liming is so effected that, after hairing and fleshing (the lime being more easily soluble) the skins require less bateing or puiring and the hides less working and de-liming previous to passing to the liquors.

(9) The quantity of lime precipitated and combined can be regulated simply and accurately to suit any class of hides or skins; the skins cannot therefore be over-limed, even if left in the final solution for days, and in consequence strictly uniform results will always be obtained.

The following is a report on Messrs Pullman's process for liming hides and skins by Dr T. Gordon Parker :—

"At the request of Messrs John and Edward Pullman, I visited the works of Messrs R. & J. Pullman, Ltd., on the 11th January, in order to investigate the working of their new process for liming hides and skins.

"On my arrival at the tan-yard, a pack of salted Queensland hides, averaging 60 lbs., had been got ready for the process of soaking in water by the ordinary methods. I examined the hides, and considered that they were in a suitable condition for liming, freed from salt and other extraneous matters, and also soft and pliable. The pack was divided into two lots, one of which was treated in a drum, the second lot being treated in a paddle. No. 1 pack was now put into the first solution in a large drum, and slowly drummed in this for about two hours, at the end of which time they were thoroughly plumped up, were soft and soapy in feel, and exactly what one would expect from treating hides in such a solution as was used. I cut off a small piece from one of the hides at this stage, which was afterwards examined microscopically. It appeared to be in a healthy condition, the fibres were swollen and separated, but not in any way destroyed or damaged. "These hides were now taken out of the drum and put into a second bath, which consisted of a solution in correct proportions, to produce, in conjunction with the materials used in the first bath, calcium hydrate (lime) in the interior of the hide. After drumming

in this second solution for about two hours, the hides were again examined, and it was found that by the joint action of the two solutions used, lime had been deposited in the interior of the hide and chemically combined with the hide substance. The hides appeared to be exactly the same in appearance and feel as the best lime hides would appear on being drawn from the last lime in any up-to-date tanyard. They were well pumped, firm, and appeared to be in a perfect and healthy condition. A section was cut from one of the hides and afterwards examined, both chemically and microscopically, in my laboratory; the fibres were thoroughly separated and in perfectly healthy condition. "The solutions through which the hides had passed were examined, and found to contain no dissolved hide substance, only containing the usual substances which are removed from the hide by the action of ordinary lime. On the removal of the hair, the grain was firm, not drawn or loosened in any way; in fact, it would be impossible to distinguish these hides from any thoroughly limed pelt.

66

Precisely the same results were obtained in experiment No. 2, which was carried out in a paddle instead of in a drum, the only difference being that the process took slightly longer, both in the first and second baths, and, as is only natural, the hides appeared slightly firmer.

"On the 20th January I again visited Messrs Pullman's works, Godalming, in order to see a pack of hides which had been in ordinary pits instead of being paddled or drummed.

"I watched these hides being unhaired, and examined them carefully. They were in an equally good condition to the packs examined. on the 11th. The hides had a nice mild feel, a perfectly smooth and even grain, were firm and plump, and appeared most admirably suited for the manufacture of either sole or dressing leather. A sample of the hair was taken from both packs and examined microscopically. It was absolutely undamaged by the action of either of the chemicals, and perfectly suitable for felting, or any other purpose for which ordinary hair can be used.

"The pelt was examined, and found to contain the average quantity of lime, but, what I considered most important, was almost free from grease, the action of the solution in the first bath having saponified the natural grease of the hide, forming a soluble soap, which would be dissolved out. This, in my opinion, is a very important matter, as it does away with, or at least diminishes, the evil of greasy leather, a serious evil at some periods of the year.

"The process appears to me to be one of the most important improvements that has been recently introduced into the leather trade, because the process is applicable to every branch; and possesses, in my opinion, the following important advantages:-That the quantity of lime precipitated and combined in the hide may be regulated, simply and accurately, to suit any class of hides or skins; hides cannot be over-limed even if left in the final solution for days; that the natural grease of the hide is not, as in the ordinary liming process, transformed into an insoluble soap, but a soluble soap is first produced, which is largely dissolved out, thus removing the natural grease from the hides, and preventing the production of greasy leather; that the long handling and hauling process at present in vogue will be completely done away with, and by Messrs Pullman's process the heaviest hides may be limed and unhaired in from eight to twelve hours; the dangers of old limes and consequent destruction of pelt substances, meaning loss of weight, will be absolutely obviated. The process will save very largely in the quantity of water used in tan-yards. In some districts this will prove a great blessing, and thus what is now getting such a serious matter, the quantity of sewage from the tan-yards, will be materially decreased, as it is the lime liquors which are usually the most objectionable in the pollution of rivers and streams, and so strongly objected to by the local authorities at sewage outfalls. The space required for the process will be much smaller; one pit will serve where by the present process ten or more are in use; and at the same time the cost of the process would be materially cheaper than the present process of liming; and last, but not least, the quality of the pelts produced would always be identical, provided the materials are weighed out correctly. This is a most simple matter, as the materials can be bought in liquid form of known strength, and the proportions can by any intelligent workman be measured out accurately; even a slight error in the proportions used would not have a serious effect. The pelt would thus never be over-limed or under-limed, as at present is frequently the case. Lime speck, lime blast, lime burns, hook scratches and the many other common flaws due to carelessness in the present process, can be absolutely obviated, and there will be no lime slab, which is frequently a serious nuisance to get rid of. Another point which is also of importance, is that the process can be used with impure water, an especial advantage being that when used with water contaminated with iron the iron is precipitated out, and no evil effects of it communicated to the leather.

"I was also shown at Messrs Pullman's works several different classes of skins which had been treated by the same process, which proved to me that it was equally suitable for any class of skin or hide, from the lightest to the heaviest, a piece of walrus being an example of the heavier class. This was thoroughly limed and free from grease.

"In conclusion, from careful observation, examination of the pelt, both before and after, and also of the liquors used, I am strongly of

the opinion that the process will prove a valuable one to the leather trade in general, that the cost of production will be reduced and the leather improved in quality.

"I consider the process very simple, perfectly reliable, and entirely novel."

It is possible that in the neighbourhood of paper and bleachworks the waste soda liquors from the one and waste CaCl, liquors from the other may be utilised advantageously in the above process of liming.

The liquors from the tan-pits are sufficiently objectionable both in character and appearance to call for special treatment. When they are reused as far as possible and the volume kept low, a Kestner evaporator as described in Chapter VIII. might be adopted advantageously for the purpose of getting the liquors sufficiently dense to permit of their being carried away to the manure heap.

Where the volume is too great to permit of this, precipitation by means of alumina sulphate-not alumina-ferric, which causes a black discoloration due to iron and tannic acid-might be resorted to, and followed by a separate 'septic' or decomposing tank and bacterial filters as in fig. 75. From trials made by the author, he is led to believe that a different type of organism is cultivated on separate filters used in this way, as such filters in toto give far better results per square yard than a single filter treating a like quantity of the liquors mixed proportionately.

CHAPTER V.

BREWERY AND DISTILLERY WASTE.

THE waste liquids discharged from breweries are due to the washing of returned casks (many of which contain old beer, hops, etc.), and the various utensils, plant and floors; for no one knows better than the successful brewer that absolute cleanliness is essential to the production of good beer.

Before little or anything was known of wild growths' by aërial infection, brewers practised, and valued, cleanliness from experience; and the careful washing of mash tuns, hop backs, coolers, fermentation vats and barrels has always been an important part of brewery work.

These waste wash liquors are loaded with vegetable organic matter of a fibrous or cellular character in suspension, with albuminoid bodies, the various transformations of starch due to inversion by diastase, like enzymes, and fermentation by yeast, as well as with artificial dextrose where such malt substitutes are used, in solution, in addition to the usual scouring and fining agents, both in solution and suspension.

The waste discharged by distilleries, pot ale principally, or beer from which the alcohol has been distilled, has much the same character but is more concentrated. In both cases the earliest contribution to the drains (malt steeping omitted) after the washing of hot or cold (clean water) tanks is the washing of the mash tun. A residual portion of both wort and grist, or grains, together with any cleaning agents, form the burden of this. An analysis of the wort itself may be taken as given by Heron,* as follows: