Found this article on how they used to tan leather:
OF THE “PURE” FINDERS
Dogs’ – dung is called ‘pure’ from its cleansing and purifying properties.
The name of “pure finders” however has been applied to the men engaged in collecting dogs’-dung from the public streets only within the last twenty or thirty years. Previous to this period there appears to have been no men engaged in the business, old women alone gathered the substance, and they were known by the name of “bunters,” which signifies properly the gatherers of rags; and thus plainly intimates that the rag gatherers originally added the collecting of ‘pure’ to their original and proper vocation. Hence it appears that the bone grubbers, rag gatherers and pure finders, constituted formerly but one class of people, and even now they have, as I have stated, kindred characteristics.
The pure finders meet with a ready market for all the dogs’- dung they are able to collect, at the numerous tanyards in Bermondsey, where they sell it by the stable bucket full, and get from 8d. to 10d. per bucket, and sometimes from 1s. to 1s.2d. for it, according to its quality. The dry ‘limy –looking ‘sort fetches the highest price at some yards as it is found to possess more of the alkaline or purifying properties; but others are found to prefer the dark moist quality. Strange as it may appear, the preference for a particular kind has suggested to the finders of Pure the idea of adulterating it to a very considerable extent; this is effected by means of mortar broken away from old walls, and mixed up with the whole mass, which it closely resembles; in some cases however the mortar is rolled into small balls similar to those found. Hence it would appear, that there is no business or trade, however insignificant or contemptible, without its own peculiar and appropriate tricks.
The pure-finders are in their habits and mode of proceeding nearly similar to the bone-grubbers. Many of the pure-finders are however, in better circumstances, the men especially, as they earn more money. They are also to a certain extent, a better educated class. Some of the regular collectors of the substance have been mechanics and other small tradesmen, who have been reduced. Those pure-finders who have a ‘good connection’ and have been granted permission to cleanse some kennels, obtain a very fair living at the business, earning from 10s. to 15s. a week. These however are very few; the majority have to seek the article in the streets, and by such means they can obtain only from 6s. To 10s. A week. The average weekly earnings of this class are thought to be about 7s. 6d.
From all the enquiries I have made on this subject, I have found that there cannot be less than 200 to 300 persons constantly engaged solely in this business. There are about 30 tanyards large and small in Bermondsey, and these all have their regular pure collectors from whom they obtain the article. At Messrs Leomont and Roberts there are 23 regular street finders who supply them with pure. This company do more business in the branch of tanning in which the article is principally used, viz., in dressing the leather for book- covers, kid-gloves, and a variety of articles. Besides these, it may be said that the numbers of the starving and destitute Irish have taken to picking up the material, but not knowing where to sell it, or how to dispose of it, they part with it for 2d. Or 3d. a pail full to regular purveyors if it to the tanyards who of course make a considerable profit by the transaction. The children of the poor Irish are usually employed in this manner, but they also pick up rags and bones, and anything else which may fall in their way.
I have stated that some of the pure-finders, especially the men. Earn a considerable sum of money per week; their gains sometimes as much as 15s.; indeed I am assured that seven years ago when they got from 3s. to 4s. per pail for the pure, that many of them would not exchange their position with that of the best paid mechanic in London. Now however the case is altered, for there are twenty now at the business for every one who followed it then; hence each collects so much less for the article. Some of the collectors at present do not earn 3s. a week, but these are mostly old women who are feeble and unable to get over the ground quickly; others make 5s. to 6s. in the course of the week, while the most active and those who clean the kennels of the dog fanciers mat occasionally make 9s. and 10s. and even 15s. a week still, but this is a very rare occurrence. The kennel pure is not much valued, indeed many of the tanners will not even buy it, the reason is that the dogs of the ‘fanciers’ are fed on almost anything, to save expense; the kennel cleaners consequently take the precaution of mixing it with what is found in the street, previous to offering it for sale.
The pure-finder may at once be distinguished from the bone-grubber and rag-gatherer; the latter as I have before mentioned, carries a bag, and usually a stick armed with a spike, while he is most frequently to be met with in back streets, narrow lanes, yards, and other places, where dust and other rubbish are likely to be thrown out from the adjacent houses. The pure-finder, on the contrary is often found in the open streets as dogs wander where they like. The pure-finders always carry a handle basket, generally with a cover, to hide the contents, and have their right hand covered with a black leather glove; many of them however dispense with the glove, as they say it is much easier to wash their hands than to keep the glove fit for use. Thus equipped, they may be seen pursuing their avocation in almost every street in and about London, excepting such streets as are now cleansed by the ‘street orderlies’ of whom the pure-finders grievously complains being an unwarrantable interference in the privileges of their class.

OF THE “PURE” FINDERS
Dogs’ – dung is called ‘pure’ from its cleansing and purifying properties.
The name of “pure finders” however has been applied to the men engaged in collecting dogs’-dung from the public streets only within the last twenty or thirty years. Previous to this period there appears to have been no men engaged in the business, old women alone gathered the substance, and they were known by the name of “bunters,” which signifies properly the gatherers of rags; and thus plainly intimates that the rag gatherers originally added the collecting of ‘pure’ to their original and proper vocation. Hence it appears that the bone grubbers, rag gatherers and pure finders, constituted formerly but one class of people, and even now they have, as I have stated, kindred characteristics.
The pure finders meet with a ready market for all the dogs’- dung they are able to collect, at the numerous tanyards in Bermondsey, where they sell it by the stable bucket full, and get from 8d. to 10d. per bucket, and sometimes from 1s. to 1s.2d. for it, according to its quality. The dry ‘limy –looking ‘sort fetches the highest price at some yards as it is found to possess more of the alkaline or purifying properties; but others are found to prefer the dark moist quality. Strange as it may appear, the preference for a particular kind has suggested to the finders of Pure the idea of adulterating it to a very considerable extent; this is effected by means of mortar broken away from old walls, and mixed up with the whole mass, which it closely resembles; in some cases however the mortar is rolled into small balls similar to those found. Hence it would appear, that there is no business or trade, however insignificant or contemptible, without its own peculiar and appropriate tricks.
The pure-finders are in their habits and mode of proceeding nearly similar to the bone-grubbers. Many of the pure-finders are however, in better circumstances, the men especially, as they earn more money. They are also to a certain extent, a better educated class. Some of the regular collectors of the substance have been mechanics and other small tradesmen, who have been reduced. Those pure-finders who have a ‘good connection’ and have been granted permission to cleanse some kennels, obtain a very fair living at the business, earning from 10s. to 15s. a week. These however are very few; the majority have to seek the article in the streets, and by such means they can obtain only from 6s. To 10s. A week. The average weekly earnings of this class are thought to be about 7s. 6d.
From all the enquiries I have made on this subject, I have found that there cannot be less than 200 to 300 persons constantly engaged solely in this business. There are about 30 tanyards large and small in Bermondsey, and these all have their regular pure collectors from whom they obtain the article. At Messrs Leomont and Roberts there are 23 regular street finders who supply them with pure. This company do more business in the branch of tanning in which the article is principally used, viz., in dressing the leather for book- covers, kid-gloves, and a variety of articles. Besides these, it may be said that the numbers of the starving and destitute Irish have taken to picking up the material, but not knowing where to sell it, or how to dispose of it, they part with it for 2d. Or 3d. a pail full to regular purveyors if it to the tanyards who of course make a considerable profit by the transaction. The children of the poor Irish are usually employed in this manner, but they also pick up rags and bones, and anything else which may fall in their way.
I have stated that some of the pure-finders, especially the men. Earn a considerable sum of money per week; their gains sometimes as much as 15s.; indeed I am assured that seven years ago when they got from 3s. to 4s. per pail for the pure, that many of them would not exchange their position with that of the best paid mechanic in London. Now however the case is altered, for there are twenty now at the business for every one who followed it then; hence each collects so much less for the article. Some of the collectors at present do not earn 3s. a week, but these are mostly old women who are feeble and unable to get over the ground quickly; others make 5s. to 6s. in the course of the week, while the most active and those who clean the kennels of the dog fanciers mat occasionally make 9s. and 10s. and even 15s. a week still, but this is a very rare occurrence. The kennel pure is not much valued, indeed many of the tanners will not even buy it, the reason is that the dogs of the ‘fanciers’ are fed on almost anything, to save expense; the kennel cleaners consequently take the precaution of mixing it with what is found in the street, previous to offering it for sale.
The pure-finder may at once be distinguished from the bone-grubber and rag-gatherer; the latter as I have before mentioned, carries a bag, and usually a stick armed with a spike, while he is most frequently to be met with in back streets, narrow lanes, yards, and other places, where dust and other rubbish are likely to be thrown out from the adjacent houses. The pure-finder, on the contrary is often found in the open streets as dogs wander where they like. The pure-finders always carry a handle basket, generally with a cover, to hide the contents, and have their right hand covered with a black leather glove; many of them however dispense with the glove, as they say it is much easier to wash their hands than to keep the glove fit for use. Thus equipped, they may be seen pursuing their avocation in almost every street in and about London, excepting such streets as are now cleansed by the ‘street orderlies’ of whom the pure-finders grievously complains being an unwarrantable interference in the privileges of their class.
