March 1, 1865.] THE TECHNOLOGIST. 



ON CHEMISTRY APPLIED TO THE ARTS. 347 



of a strong solution of glue, will keep it perfectly sweet for at least two 

 years, and probably for an indefinite period. Also, if bides or skins 

 are immersed for twenty-four hours in a solution of one part of carbolic 

 acid to fifty of water, and then dried in the air, they will remain quite 

 sweet. In fact, hides and bones so prepared have been safely imported 

 from Monte Video. From these facts and many others with which I 

 am acquainted, I firmly believe that this substance is destined, within a 

 few years, to be largely used as an antiseptic and disinfectant. I need 

 hardly speak of the power of chloride of sodium, or common salt, in 

 preserving animal matters, and it is highly probable that the interesting 

 process described by Mr. J. Morgan, for the employment of salt, is likely 

 to render great service in preserving animal food from putrefaction. 

 But with regard to the feasibility of its use in Monte Video and Buenos 

 Ayres, I cannot offer an opinion, as it depends upon so many local cir- 

 cumstances which it is impossible to appreciate here. Messrs. Jones and 

 Trevethick displayed at the last Exhibition some meat, fowls, and game 

 preserved by the following process, which received the approbation of 

 the jurors. Meat is placed in a tin canister, which is then hermetically 

 closed, with the exception of two small apertures in the lid. It is then 

 plunged into a vessel containing water, and after the air has been ex- 

 hausted through one aperture by means of an air pump, sulphurous acid 

 gas is admitted through the second aperture, and the alternate action of 

 exhausting the air and replenishing the sulphurous acid gas is kept up 

 until the whole of the air has been removed. The sulphurous acid gas 

 in its turn is exhausted, and nitrogen admitted. The two apertures are 

 then soldered up, and the operation is completed. As I consider the 

 action of carbon on animal matters rather as a case of oxidation than of 

 preservation, I shall refer to that subject further on, and shall, there- 

 fore, proceed to consider the employment of certain animal matters not 

 yet alluded to during this course of lectures, such as the flesh of dead 

 animals not used as food, and those other parts of their carcases which 

 have not been applied in any of the processes already described. The 

 greatest part of these refuse matters are used for producing animal 

 black, which differs from bone black, referred to in my first lecture, 

 being used in the state of impalpable powder, whilst bone black or char 

 is composed of small hard grains. The manufacture of animal black is 

 generally carried out by introducing into horizontal retorts connected 

 with a coil or condenser, and with an exit pipe for the gases, some of the 

 animal matters mentioned ; on the application of heat decomposition 

 occurs, the oily matters distil and condense in the worm, and constitute 

 what is called oil of dippel, formerly much used in the art of currying 

 certain classes of leather ; water also distils, charged with a variety of 

 ammoniacal salts, which are generally converted into sulphate of ammo- 

 nia for agricultural purposes. As to the gases, they are usually ignited 

 ' and burnt to waste. The carbonaceous mass which remains in the re- 

 tort is removed, and ground to powder with water in a mill, allowed to 



