The fellmonger prepares skins for the leather-dresser, the chief operations being taking off the wool, liming the skins, etc. The skins deprived of wool are called “pelts.” The pelts are thrown into a pit containing milk of lime, and thence sent direct to the leather-dresser. Nuisance may arise from (1) the odour of the raw skins; (2) the ammoniacal odour from the lime-painted skins hanging in the yard; (3) the emptying and cleansing of the “poke” or tank in which the hides are washed; (4) the foul condition of the waste lime taken from the exhausted lime pits; (5) the odour from the dirty unpaved yards.
The leather-dresser only deals with “pelts,” derived from sheep-skins; the tanner with bullocks’-hides. The skins brought from the fellmonger to the leather-dresser are first deprived of lime, and then soaked in a solution of dog’s dung, called “pure,” until they become soft. In winter this “pure” solution is warmed for use. The odour is very abominable, both from the “pure” tub, and from the discharge of the exhausted “pure” liquid into the drain.
At each stage of tanning nuisance may arise unless great precautions are taken, as when the hides are soaked in lime and water, when the hair is being removed, when the loose inner skin of the hide is being removed, and especially when the hides are soaked in pits containing pigeons’ or other dung. Nuisance may arise again during the passage of offensive hides through the street. Cleanliness is the great rule. If every process is carried on with due precaution, including frequent washing out of receptacles and the free use of disinfectants, little complaint need arise.
The manufacturers of glue and size boil out the gelatine from bits of hides and “fleshings” from leather dressers and tanners, from damaged “pelts,” ox or calves’ feet, horns, and other similar substances. The raw material is apt to be offensive in collection or while accumulating on the premises. The process of boiling causes offence by the effluvia from the steam. The residue remaining after the process is known as “scutch,” and this, unless frequently removed, is a most serious source of nuisance.
Prussiate of Potass is manufactured by heating carbonate of potass with refuse animal matters. In order to avoid nuisance the pot in which the boiling is done should have a pipe to conduct away the steam, first running horizontally and then vertically down to the back part of the fire.
Fat-melting and Dip-candle-making, as usually carried on, give rise to nuisance. The fat which is melted down usually comes from butchers and marine-store dealers in a rancid or even putrid condition, and it may be stored on the premises for some time before it is boiled. The vapours from the melting-vat are very offensive. They should be carried by means of a pipe down until they discharge just under the boiler-fire. The residue from the fat-melting process (known as “greaves”) requires frequent removal to avoid nuisance.
Bone-boiling, in order to extract the fat and gelatine, is most offensive, and most difficult to deal with. After boiling, the bones are apt to give off offensive smells. The vapours from the closed boiler should be condensed as far as possible in a worm condenser, and the remainder passed through a furnace fire.
In the manufacture of artificial manures nuisance is apt to arise (1) from the reception and accumulation of the raw materials, as putrid fish, putrid blood, scutch (the residue from the manufacture of glue), recently boiled bones, etc.; (2) from the preparation of the raw material for use. Thus the drying of condemned fish or meat on open kilns is very offensive; similarly the drying of sewage sludge. (3) From the process of mixing the materials of manufacture, irritant and offensive vapours being evolved, as for instance in the manufacture of manure by crushing bones, and converting into super-phosphate by the addition of sulphuric acid. (4) From the removal of the manure from the hot den, after it has been dried. When sulphuric acid is mixed with coprolites or other mineral phosphates, most irritant and offensive vapours are produced, which may be perceived in some cases at the distance of a mile.
Blood-boiling is now almost obsolete, having been replaced by albumen-making and clot-drying. Nuisance may arise from the blood collected from slaughter-houses being in a putrid state; and from the effluvia evolved during the drying process.
Gutscraping, gut-spinning, and the preparation of sausage-skins are very closely akin. In gut-scraping the putrid intestines are deprived of their interior soft parts by scraping with pieces of wood, and are then, after being cleansed, ready for sausage-skins. In gut-spinning the prepared gut is twisted into a cord. The small intestines of hogs and sheep are used for this purpose. The stench from these establishments is indescribably horrible. Extreme cleanliness is desirable. Immersion of the guts in common salt is useful; so also the use of impervious vessels, early removal of all refuse material, etc.