|{^ Scietitific Notices — Miscellaneous. [Aug, 



air. Tlie piston is again forced clown below the opening C, the 

 air in the receiver rushes into the barrel, and is again expelled 

 by the ascending piston. 



Since the air in the receiver has no valve to open by its 

 elasticity, it is obvious that there is no limit to the degree of 

 exhaustion, as in the common construction. (Ed. New Phil. Jour.) 



8. Hardening of Steel Dies. 



Mr. Adam Eckfeldt is stated to be the first who employed the 

 following successful mode of hardening steel dies. He caused 

 a vessel, holding 200 gallons of water, to be placed in the upper 

 part of the building, at the height of forty feet above the room 

 in which the dies were to be hardened ; from this vessel the 

 water was conducted down through a pipe of one inch and a 

 quarter in diameter, with a cock at the bottom, and nozzles of 

 different sizes, to regulate the diameter of the jet of water. 

 Under one of these was placed the heated dies, the water being 

 directed on to the centre of the upper surface. The first expe- 

 riment was tried in the year 1795, and the same mode has been 

 ever since pursued (at the Mint) without a single instance of 

 failure. 



By this process the die is hardened in such a way as best to 

 sustain the pressure to which it is to be subjected ; and the 

 middle of the face, which, by the former process, was apt to 

 remain soft, now becomes the hardest part. The hardened part 

 of the dies so managed, were it to be separated, would be found 

 to be in the segment of a sphere, resting in the lower softer part 

 as in a dish, the hardness, of course, gradually decreasing as 

 you descend toward the foot. Dies thus hardened preserve 

 their forms till fairly worn out. — (Franklin's Journal.) 



9. Cutaneous Absorption, 

 The following experiments on this subject have been made by 

 M. Collard: — 1. Having immersed his hands as far as the wrists 

 in hot water for two hours and a half, he found that the veins 

 of the hand and fore arm were swelled, and also the lymphatic 

 ganglions in the axilla. 2. Having kept his hands for an hour 

 in a vessel filled with water, of which he had ascertained the 

 capacity and surface, he found, on withdrawing them, that the 

 vessel had lost more water than another placed as exactly as 

 possible in the same circumstances. 3. A funnel being closed 

 oelow and filled with water, the hand was applied to the upper 

 part; the portion of skin within the funnel was gradually drawn 

 inwards, as if by the formation of a small vacuum. 4. The ex- 

 periment was repeated with a funnel, the neck of which was 

 graduated, and in which was a bubble of air, to indicate by its 

 position any absorption ; the results coincided with the last. 

 h» A glass syphoa had its shortest leg enlarged into a funnel^ 



