US83433A - Improved process and composition for tanning leather - Google Patents

Description

aters e; z rr rnor NEW YORK, N.'Y., ASSIGNOR TO HIMSELF AND WERNER WERNER, or SAME PLACE. Latte rs Ma. No. 83,433, at; October 27, 1868.

' IMPROVED PROCESS AND COMPOSI'I'IQN FOR TANNING- LEATHER.

The Schedule referred to these Letters Patent and making part'of the same.

To all whom 'it may comer-n:

Be it known that I, G. ZIPBE, of New York, in the county of New York, and State of New York, have invented a new and improved Process of and Composition for Tanning Leather; and I do hereby declare that the following is a full, clear, and exact description thereof,.whichjwill enable-others skilled in the art to make and use the same.

This invention relates to a new tanning-composition, which is so compounded that the leather can be completely tanned in a few days, while heretofore it took months to do it.

My invention consists more. particularly in the use of a new composition, in which the leather is steeped, or, rather, with which it is impregnated; also, of a new soaping-compound for binding the metallic ingredients of the former composition, and for making the leather water-tight.

The iuventiolralso consists of the process of treating the leather during. the tanning-operation.

The following is a description of the process and composition used I The skins are, after the hair has been removed, first steeped in a solution of sugar of lead, its strength being about 'i Baum, in which they remain about twenty-four hours. They should be taken outevery now and then, to let the liquid drop ofi, and then be steeped again. The skins having thus been prepared for the impregnating-compound, are then steeped in the same.

'This compound consists of about- Fifty parts of alcohol.

One hundred parts of water.

Seventy-two parts of sulphate of iron.

Sixteen parts of sulphm-ic acid.

Thirty-six parts of powdered manganese.

Twelve parts of sirup.

Twelve parts of common salt.

Three parts of chlorochromio acid.

I prepare the chlorochromio acid by fusing together in a tubulated retort ten parts of chloride of sodium and sei' nteen palts of bichromate of potassa, and dis-1 tilling tll'e anass with thirty parts of strong sulphuric acid.

Instead of thechlorochromic acid as prepared above, I also use an impure acid, prepared by simply heating together the chloride of sodium, bicln'omate of potash, and sulphuric acid, untildeconiposition takes place.

Tocthis mixture is gradually added so much carbonate of soda as it can sustain without forming a .last-ing precipitate.

The sulphate -of iron is first dissolved .in boiling (water. This 'mixture is well stirred with a wooden ladle, and then the sulphuric acid is added. This acid unites partly with the iron, forming sulphurous oxide of iron.

The manganese is then added, and completely con- .verts the..sulphurous oxide. into oxide of imn, also forming sulphate of manganese. One part of the oxide remains unbound in the solution, but will be absorbed, when the skins are inserted, by the acid contained in the leather, and liberated from the same.

The solution is then left standing for about thirty minutes, and then the chlorochromic acid is added.

The salt and sirup are also put in, while the compound is being well stirred, and, finally, after the liquid has cooled down to about 99 Fahrenheit, the alcohol is put in. p

The chlorochromic acid is only added to impart the requisite color to the leather. It may therefore be omitted, if desired, or its quantity be diminished or increased at will. The more of it is taken, the lighter will the leather become.

The application of the sugar-of-lead solution is not imperatively necessary. It does, however, produce a' finer and denser leather, as it causes sulphurous oxide of lead to be retained in the leather, whereby such leather is made more pliable and soft, which is par-- ticularly important for thick being hammered.

The impregnating-composition can be made cheaper by leaving out the alcohol, and using water in its stead. The process of tanning would thereby,however, be extended, and the skins would, after tanning, have to be thoroughly washed to remove all traces of the acid, while the alcohol transforms the acid into ether, and makes the washing unnecessary.

The addition of alcohol does consequently produce the quickest tanning, and it also forms, in connection with the sirup, a substitute for the manipulator, as the skins will, from the mixture, come out soft and sole-leather, to allow its.

. pliable.

The sirup forms, in connection with the acid, a brown, gelatinous, viscid substance, (humic acid,) which combines also with the metallic oxide, and which prevents the fibres from pasting together, and consequently the leather from shrinking. The proportions aforementioned are intended for very thick leather, to bring the liquid to about 32 to 33 Baum. For calf-skins, it requires 16, and for the thinner skins still less. The thinner the leather, the more water is taken.

The thickest skins will require but little-more than sixteen hours to be thoroughly tanned; very thin skins, but a few minutes. At the edge the completion of the process can be readily ascertained.

The composition should have a temperature of about 99 Fahrenheit when the leather is steeped in it.

The skins are put into it, are well stirred therein, and frequently taken out and reinserted, until they are thoroughly impregnated with the liquid.

The skins are, atter having been impregnated, steeped in the soaping-compoimd, which is composed of One part of linseed.

Sixty parts of tallow-soap.

Four parts of tallow.

Nine hundred parts of water.

Nine hundred parts of alcohol.

The skins are now completely tanned, soft, pliable, and strong.

The seeping-compound serves to insolubly bind the metallic contents of the impregnating-compound to the leather, and. also to make such leather waitertight For tanning kid gloves, it is also very useful, and a substitute for the flour and yolk of eggs, heretofore used.

- The combinations which are produced in the skins during the tanning-process, and which, in the seepingeompound, are securely bound therein, produce aleather more water-tight, more pliable, stronger, and more duratble than it ever is in the ordinary well-known tanning \Vitnesses: I

Flume BLooKLnY, ALEX. .F. ROBERTS.