186 [Assembly 



tending the operation, inasmuch as the diversities in the qualities and 

 characteristics of hides render it impossible to subject them to any- 

 thing more than a general mode of treatment. 



In " sweating," the character of the hides, and the temperature, 

 are essential, but ever-varying considerations. As a general rule, 

 however, the milder the process of preparing the hides for the bark, 

 the better. Unnecessarily severe or prolonged treatment is inevitably 

 attended with a loss of gelatine, and a consequent loss of weight and 

 strength in the leather Too high a temperature is particularly to be 

 avoided. In almost every lot of hides, particularly Oronocos, how- 

 ever, there are generally some that prove very intractable — resisting 

 all the ordinary modes of softening. For such, a solution of ashes, 

 potash, or even common salt, will be found to be beneficial; and pe- 

 culiarly so in hot weather. As I have said, no precise rule can be 

 given as to the length of time required for the preliminary process of 

 soaking and " sweating," so much depending upon the qualities of 

 ■the hides, and the temperature at which these operations are conduct- 

 ed. 



The following table may, however, be found useful in conveying 

 an approximation to a definite idea of the practice of ray tannery: 



Soaking. 

 Temperature, 40° 50" 60° 70° 



Days. Days. Days. Days. 



Buenos Ayres hides, 10 to 12 8 to 12 6 to 8 3 to 6 



Carthagena and Laguira, 8 to 12 7 to 9 5 to 7 2 to 5 



Sweating. 

 Temperature, 40° 50° 60° 70° 



Days. Days. Days. Days. 



Buenos Ayres hides, 15 to 20 12 to 16 8 to 12 2 to 3 



Carthagena and Laguira,--- 15 to 20 lU to 15 6 to 8 2 to 3 



I would here remark that I changed the process from liming to sweat- 

 ing, for the sole leather, in 1836 — the only change in tanning I have 

 made for twenty years; and for heavy sole leather, it has been prov- 

 ed to be quite as good as liming, if not better, and somewhat cheap- 

 er; besides yielding a greater gain of weight, and when tanned, 

 making leather more impervious to water. Liming and " bating," 

 however, for upper and light leather, is preferable; and, if the same 



