104 ANNUAL OF SCIENTIFIC DISCOVERY. 



an opening at its apex, over which a deflecting plate is placed. The whole 

 is so arranged that the boiling liquid will pass up through the opening in 

 the apex of the cap and striking against the deflecting plate, will run down 

 again into the vessel. The liquid is thus effectually prevented from passing 

 over the sides of the vessel. 



DURABILITY OF GUTTA PERCIIA. 



Some interesting statements respecting the durability of gutta percha 

 have recently been made public. From an inspection of the underground 

 wires of the British Telegraph Company, conducted by Mr. E. Highton, it 

 appeared that they had decayed wherever they had passed near the roots of 

 an oak. On examination, the root and gutta percha were found to have 

 both been attacked by a yellowish white fungus, which had destroyed the 

 gutta percha wherever brought into contact with it. This was not found to 

 be the case under any other tree, but at Winslow such wire as has had been 

 inclosed in iron piping was found to be decayed, while that in the usual 

 wooden troughs was sound. Here the destruction was evidentlv not the 



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work of fungi : but Mr. Highton's experiments have led him to the conclu- 

 sion that the spawn of the common agaric, and presumably of its congeners 

 also possesses the property of decomposing gutta percha ; and it is said that 

 Dr. O'Shaughnessy has found the telegraphic wires sent out to India unser- 

 viceable, on account of the disintegration of their gutta percha envelops. 

 Considering how extensively the gum has come to be used, these facts must 

 be thought to deserve attention. 



IMPROVEMENTS IN TANNING. 



At a recent meeting of the N. Y. Mechanics' Institute, Professor Mapes 

 described a new centrifugal apparatus by which he bad been enabled to force 

 the tannic acid through every part of the raw hide by means of centrifugal 

 force generated in a rapidly revolving perforated cylinder resembling the 

 sugar machines. 



By the prevailing modes it requires about seventy days to tan completely 

 the average of raw hides, while by the improved process Professor Mapes 

 said that he had succeeded in tanning a calf skin thoroughly in less than 

 fifteen minutes. The process he used was to place the hide around the in- 

 side of the cylinder, and holding it there by means of the centrifugal force 

 resulting from a very high velocity, and then passing a stream of tan liquor 

 into the centre, which was then carried by the centrifugal force against the 

 hide, and passed through under the intense pressure, after which it escaped 

 through the perforated cylinder into a surrounding vat, and was returned to 

 perform the same journey over again until the tannic acid was exhausted. 

 Mr. Schultz stated that he had experimented with the hydrostatic column in 

 the tanning of calf skins, and found that the process produced the most 

 positive results, the raw hide being thoroughly tanned in about fifteen min- 

 utes the height of column being about twenty-five feet. 



