SS Esper'imenti and Obfervatlons on Tanning. 



The intelligent manufadurer will readily perceive that this new method is jrounded on 

 two particular clreumftances, belides a more fcientlfic management of the general procefs 

 than has been ufu.il. T\\c firft confifts in the method of determining the prcfencc and 

 quantity of the tanning principle, by the hydrometer and the precipitation of glue : the 

 fecond^ in applying tliis principle in a concentrated Hate, more early in point of time 

 than has, perhaps, been hitherto done. Our tanners, after the common previous procelTcs 

 and unh.iiring by acii's, by lime, or by piling the hides that they may heat and begin to pu- 

 trefy, apply the folution of tan, which they call ouze, in a great number of pits in the tan- 

 yard. They begin with tlie weakcfl folution, which has been ufed, and is of a lighter colour 

 than tlie other. And they pafj the hides, according to their judgment and experience, into 

 ouzes which are (tronger and ftronger, until -at laft, in certain cafes, the hides come to be 

 buried for a certain time in a folid mafs of tan or oak-bark. The oak-bark itfelf, in the 

 pits, is not only the fource from which the water extrafls the tanning principle ; but feems, 

 likcwife, In fome meafure, during the lafl: ftages of the procefs, to operate mechanically by 

 keeping the furfaces of the hides from touching each other. 



On the occafion of this apparently important difcovery, I applied to r>r.: of the firtl manu- 

 fafturing houfes in the Borough of Southwark, to make enquiries cciicorning its value. One 

 of the partners, who appeared to have paid confiderable attention to the proccfles of his 

 manufactory, informed me, that the flrong folution obtained from tan had been well known 

 to them for fome years under the name of eflence of tan ; and that it had been propofed to 

 ufe it as the means of bringing out the complete leather in a Ihort time. ^ 1 alked whether 

 the objedion to its ufe might confift in the outer part of the flcin becoming more pcr- 

 fedly tanned in a (liort time than the inner part; fo as to defend this lad from the fub- 

 fcqucnt change that might have taken place by a (lower operation. He anfwered, that this 

 was partly the rcafon why it was neceflary that the ouzes (hould be gradually applied from 

 the lowed to the higheft (Trength. But the chief reafon he urged in favour of the fiow pro- 

 cefs was, that the hides were found to feed and improve in their quality by remaining in the 

 pit. I could not gain fatisfaiflory information what the nature of this fcedingand improvement 

 might be. The facl, as loofcly Hated, appeared to be, that the Ikin became much thicker, 

 denfer, and heavier iir the Crft ouzes during a certain time; and that thefe advantages of 

 thlcknefs, denGty, and weight continued to exift in 'a certain degree to the very end of 

 the entire procefs. For, as he remarked, they know very well that, by bringing the (kins 

 more haftily into the flronger ouzes, they will be fooner converted into leather ; and that- 

 a (kin which ordin-irily requires fifteen months, might be tanned in nine. But then, added 

 he, the (kin which comes forward in nine mouths, from its thinnefs, and other inferior 

 qualities, will afford ninepenny foles for flioes; whereas, if it had undergone the longer pro- 

 cefs, the foles would have been worth a (liilling : — a difference which largely repays the 

 common intereft of capital for the excefs of time. 



On the other hand it may be remarked, that rcfults of this nature require to be grounded 

 on experiments carefully undertaken, under ciicumftances diiTering only with regard to the 

 objcft of invefligation, and often repeated. It does not appear from my enquiries that this 

 has ailually been the cafe ; and I have been informed that excellent leath'er has been pro- 

 duced in the new method. But I have heard nothing of its appearance in the market, 

 though upwards. of a year has clapfed fmcc tliis patent was fealed. 



A very 



