WATER-PROOF. 



' fluidity of the oil itfelf alfo facilitates its paffage into the 

 leather. 



To make the leather imbibe the fat, he propofes three or 

 four days immerfion in running water, to drive out the air; 

 then to foak the leather in melted fat, of the temperature of 

 167 degrees of Fahrenheit, till all the water in the leather 

 is evaporated by the heat ; the fat would then penetrate 

 into the interior pores of the leather, and render it imper- 

 meable to water. 



If leather is comprelTedjit evidently diminiihes the thick- 

 nefs, and increafes its compaftnefs ; and if it is beaten with 

 an iron hammer upon a very fmooth anvil, it produces a 

 permanent contraftion of its pores. Leather is in that re- 

 fpeft very much like iron, and all other metals which 

 harden by beating ; and, confequently, our author fuggefts 

 that it would be of great advantage to comprefs the leather 

 before it is ufed, by paffing it between a pair of rollers, 

 fuch as are ufed to flatten metal : this would ftiffen the 

 leather. 



It appears from experiment that the ftrong fole-leather, 

 by being properly impregnated with fat, and comprefled in 

 the rollers, abforbs only one-thirteenth part of water, im- 

 bibed by the fame leather which has not undergone thofe 

 operations. The quantity of water which the firil abforbs, 

 and which amounts to about one-thirtieth part of its weight, 

 is fo fmall, that it does not render it capable of wetting any 

 fubftance it may come in contaft with, nor does the leather 

 appear wet when taken out of the water ; it may therefore 

 be confidered as almoft impermeable to it. 



The cow-leather, when impregnated with fat, and com- 

 prefled, abforbs about one-ninth part of the water abforbcd 

 by leather of the fame nature which has not undergone thofe 

 operations. The quantity of water abforbed by the firft; 

 amounts only to the thirty-fourth part of its own weight. 



The calf-ikin, when impregnated with fat and compreffed, 

 abforbs only one-third part the quantity of water that the 

 fame quantity of leather abforbs when it has not undergone 

 thofe operations ; and that quantity is not fo much as one- 

 fortieth part of the weight of the leather. 



In this manner, without making any alteration in the 

 ufual method of tanning, except with refpeft to the thin 

 fole-leather, it is pofTible to render leather very nearly im- 

 permeable to water, by the known operations of currying, 

 provided to them are added compreflion by rollers, and foak- 

 ing in fat, as before defcribed. The additional greafing and 

 preffing will not ienfibly increafe the price of the leather, 

 for it retains only about the fixteenth part of its weight of 

 fat. 



The leather which had pafled through the rollers was not 

 diminilhed in its llrength ; for it fupported, without break- 

 ing, weights as heavy as were fupported by leather of the 

 fame kind which had not undergone that operation. 



In 1794 Mr. Bellamy of London obtained a patent for a 

 method ot rendering leather water-proof, which he thus 

 defcribes. 



Take nut oil, one gallon ; poppy-oil, one gallon ; and lin- 

 feed-oil, two gallons ; or they may be in other proportions : 

 put them iiito an iron vefiel, and fet it over a gentle fire. 

 To every gallon of the mixed oils, put half a pound of um- 

 ber, or white copperas, fugar of lead, colcothar, or any 

 other proper drier, but obferving to ufe a larger proportion 

 than the above, when the oil is to be prepared for new 

 leather, or a lefler proportion when it is to be prepared for 

 old. 



Let the oils remain on the fire, and give it as great a de- 

 gree of heat as it can bear without burning, or cauCng it to 



rife, for fix or feven hours ; and if it will not dry fufficiently 

 continue the fame degree of heat till it does : then take it 

 off the fire, and when it is a httle cooled, it is ready to be 

 applied to make water proof leather. 



This is done by a bruih being dipped into the prepared 

 matter, and rubbed or brufhed into the leather. 



When the article is well filled with the prepared oils, lay 

 It on an even board, andfcrape off what is fuperfluous with a 

 thin iroi} tool ; then put it to dry in a warm room, and when 

 fufficiently dry it will be fit for ufe. 



For fole-leather of thick fubflance,let it be gently warmed, 

 and with a brufh or pad, made of wool or hair, rub or brufh 

 the prepared matter on the leather, till it is thoroughly fa- 

 turated ; then let it dry in a warm place, and it is ready for 

 ufe. 



The proportion of the mixtures of oils, mud be varied 

 according to the nature of the oil, and alfo according to the 

 nature of the leather, for the fame kind of oil will not 

 always have the fame qualities. 



Oils exprefled at different times will frequently have a 

 greater or lefs propenfity to finifii ; and muft, on that ac- 

 count, have more or lefs of the poppy or nut oils. If the 

 drying oil finilhes reluftantly, there muft be added a leffer 

 quantity, or none at all, of the nut or poppy oils, and a 

 fmall quantity of an elfential oil added, till it will finilh with 

 eafe and beauty. The fame kind of leather will alfo require 

 a different mode of treatment ; for if the leather be new it 

 will abound more with the natural greafe of the animal 

 which produced it, and it will require the oil to be fo ma- 

 naged as to abforb or neutralize the greafy quality, that it 

 may finifh without loading the leather, and making it un- 

 pleafant to the wearer. When this is the cafe, one-fourth 

 part of elfential oil of turpentine muft be mixed with the 

 above oils when prepared ; and vice ijer/d if the leather is 

 old. 



Another of Mr. Bellamy's receipts is as follows : to one 

 gallon of the above prepared oils add one pound of gum 

 refin, half a pound of pitch, a quarter of a pound of tar, 

 and a quarter of a pound of turpentine. Let them be well 

 incorporated with the oils, by firft heating the whole mafs 

 gently, and then increafe the fire till the whole is thoroughly 

 mixed ; or he propofes to add to the oils, gums fandarac, 

 martic, anime, copal, amber, together or feparate, or af- 

 phaltum, or one-fixth part of bee's-wax. In fhort, any 

 bituminous, refinous, or adhefive matter, which will refift 

 acids, alkalies, and water, and will unite with drying oils, 

 provided when mixed in proper proportions they do not 

 render the leather hard, or make it crack, or otherwife dif- 

 agreeable. 



In the Annales de Chemie, Mr. Hildebrand of St. Pe- 

 terfburgh propofes the three following methods of render- 

 ing fole-leather impermeable by water. 



The firft preparation is made by boiling li lb. of minium 

 with 20 lbs. of oil of linfeed, or hemp-feed; continue the 

 boiling till the metallic oxyd be entirely dilTolvcd, and the 

 mixture aflumes a carbonaceous dark brown colour : appjy 

 this compofition to the infide of the hides till they can ab- 

 forb no more of it ; then dry them, in fummer by the heat 

 of the fun, in winter before a fire. When the compofitiou 

 becomes too thick, it may be liquified by the addition of oil 

 of turpentine. 



The fecond preparation is fimply either of the fame oils, 

 in part difhydrogenated by fire ; it will ferve equally well for 

 upper leathers. 



The third preparation is a mixture of two ounces of black 



pitch with a pound of tar, melted together by a gentle heat ; 



U 2 the 



