308 PHILOSOPHICAL TRANSACTIONS. [aNNO 1778. 



plunger, so as to mix it thoroughly with the whole body of the water, as before 

 directed, and then leave it to subside the requisite time. Thus you will have a 

 2d brewing of lime-water: and you may go on in the same manner to make a 

 3d, 4th, 5th, or perhaps a 6th, or more brewings, from the original quantity 

 of lime; provided you find the lime-water continue sufficiently strong. 



11. There are 2 ways of knowing when lime-water is sufficiently strong. 

 The one is by the taste, and this a little practice will teach you to distinguish; 

 the other is, by observing a certain solid scum, like the flakes of very thin ice, 

 which collects and forms itself on the surface of the lime-water. As long as you 

 find this solid scum floating on the top of the water in the cistern, so long you 

 may conclude that there is no necessity for throwing in fresh lime. 12. But 

 when the scum ceases to appear, or you find from the taste that the lime-water 

 is not so strong as it ought to be, you must then take out the plug from the 

 bottom of the cistern, and clear it by sweeping away the gross remains of lime: 

 and after you have cleaned the cistern, begin your brewings of lime-water a 

 new, and proceed in the manner already directed, as to stirring up the lime, and 

 leaving it to settle for the necessary time, so as to have the lime-water perfectly 

 limpid. In this manner you may go on from year to year, and constantly keep 

 yourself in stock with respect to lime-water. 



13. It is this lime-water which is now to be used in making your ooze instead 

 of the plain common water; and this is all the difference between the old and 

 the new method of tanning; for when the ooze is prepared, by steeping the bark 

 in lime-water (in the letches, as you do at present, only running it through 2 

 letches) you are to make use of it in the very same way that you have hitherto 

 used the common ooze. -Every thing that relates to cleaning, liming, flesh- 

 ing, &c. is to be conducted precisely as in the old or common method of tanning; 

 and the goods are to be worked in the handlers for the requisite time, and then 

 laid away in the vats, with layers and heading of bark, just as now practised, 

 and when the leather is sufficiently penetrated with the ooze, that is, completely 

 tanned, you will take it up, dry it, and afterwards dress it according to the 

 diff^erent uses for which it is intended. Always observing however, that the 

 ooze is to be turned from one letch on another before it is used, otherwise it 

 will be apt to blacken the leather. 



14. What has been hitherto said relates only to buts and calf-skins: as to sole- 

 leather, which is prepared for the ooze by steeping it in some sour liquor, in 

 order to open its pores, and raise it (according to the tanner's phrase) the new 

 method requires a different practice from the old one. 15. In the old method, 

 tanners made use of sourings brewed generally from rye, or some other grain ; 

 but these liquors are not only troublesome to brew and to ferment, but they are 

 always uncertain as to their degree of sourness or strength, which depends on 



