1830.] Varieties. 



To measure the Force of Pressure If we 

 take a leaden bullet of any determinate dia- 

 meter, and expose it to pressure between 

 plates of harder metal made to approach each 

 other in a parallel position, the bullet will be 

 compressed or flattened on two opposite sides 

 in an equal degree ; provided the lead is 

 pure, the degree of compression will indicate 

 the amount of pressure. With a graduated 

 press of the lever kind, it will be easy to 

 form a scale of pressure corresponding to 

 the different degrees of compression until 

 the ball is reduced to a flat circular plate of 

 about one fifth of an inch in thickness, and 

 it will be found that an ordinary bullet of 

 about five-eighths of an inch diameter will 

 require a pressure of near 4000 pounds, to 

 effect this degree of flattening. Suppose, 

 therefore, we wish to measure an actual 

 pressure estimated to be nearly 20 tons, we 

 have only occasion to place ten or twelve of 

 these balls at a proper distance asunder, so as 

 not to be in contact when expanded, and 

 then to measure by good callipers, or other 

 suitable means, the compression of each 

 ball, either by its thickness or diameter,, and 

 afterwards add into one sum the particular 

 pressure due to each ball from the scale first 

 made, by using the lever press before men- 

 tioned. By this mode Mr. Bevan ascer- 

 tained the amount of friction of an iron screw 

 press with rectangular threads, to be from 

 three-fourths to four-fifths of the power ap- 

 plied ; or the actual pressure has not ex- 

 ceeded four or five tons when the calcu- 

 lated pressure, if there had been no friction, 

 would have been 20 tons. The larger the 

 ball, the greater will be the pressure neces- 

 sary to reduce it to a given thickness. An 

 ordinary leaden shot, of one-eighth of an 

 inch diameter will require nearly 100 pounds 

 to compress it to a flat plate. By using a 

 ball of five-eighths of an inch diameter, Mr. 

 B. found the actual pressure of the common 

 bench vice to be above two tons when under 

 the same force ; if there -had been no friction, 

 the pressure would have been eight tons. 

 In the practical application of these balls, it 

 will be convenient to make a small impres. 

 sion upon them with a hammer, before they 

 are placed between the plates, to prevent 

 them from rolling out of their proper posi- 

 tion ; this operation will not be found to in- 

 terfere with the result, as it is the ultimate 

 compression only that is sought, and which 

 is not affected by that of a smaller degree 

 before impressed. This property will also 

 be found very convenient, for the same sub- 

 stance may be used several times, by taking 

 care that each succeeding pressure exceeds 

 that of the preceding. The application of 

 these leaden balls to determine the actual 

 pressure, will not interfere with the regular 

 operation of a press, as the articles under 

 pressure may be in the press at the same 



95 



time the balls are used, which of course must 

 be placed between separate plates. 



Preservation of Butter The method 

 used by the Tartars consists in fusing the 

 butter in a water bath, at a temperature of 

 190 Farenheit, and retaining it quiescent in 

 that state until the caseous matter has settled, 

 and the butter become clear ; it is then to be 

 decanted, passed through a cloth, and cooled 

 in a mixture of salt and ice, or at least in 

 spring water, without which it would crys- 

 tallize, and not resist so well the action of 

 air. Preserved in close vessels and cold 

 places, it may be kept for six months as 

 good as it v/as on the first day, especially if 

 the upper part be excspted. If, when used, 

 it be beaten up with one sixth of cheese, it 

 will have all the appearance of fresh butter. 

 The flavour of rancid butter may be removed 

 almost entirely by similar meltings and cool- 

 ings. 



Steam Navigation on the Ganges Ac- 

 counts from Benares state, that the com- 

 pany's steamer Hoogly, could not be got 

 higher up the Ganges than a place called 

 Kutchwa, about 45 miles below Mirsapore, 

 and about 80 from Allahabad. Her further 

 progress was stopped by a shoal or sand reef 

 extending completely across the channel, be- 

 tween the Kutchwa and Badokee banks, the 

 greatest depth of water across which was two 

 feet six inches, the vessel at the time draw- 

 ing four feet one inch forward, and three and 

 three aft, having only 100 maunds of coals 

 on board, and the passengers and luggage, 

 and the freight having been landed. Even 

 had the steamer been able to overcome this 

 difficulty, greater still, it was believed, were 

 to be got over before she could reach Allaha- 

 bad ; and had she even succeeded in getting 

 there, it was supposed she could not be got 

 back before the setting in of the rains. Under 

 these circumstances it was deemed the most 

 advisable plan to return to Benares, and 

 there wait for further instructions. 



Action ofSEther on Sulphate of Indigo. 

 When sulphuric aether is added to sulphate 

 of indigo, in about half an hour, at a tem- 

 perature of about 30 Reaumur, the colour 

 of the indigo totally disappears, and no sub- 

 stance whatever is capable of restoring it. 

 The colourless mixture being subjected to 

 distillation, yielded a liqnor which reddened 

 litmus strongly, and gave no precipitate v/ith 

 barytic salts ; but with a solution of nitrate of 

 silver, a precipitate was obtained soluble in 

 ammonia. 



Leech Bites. Dr. Towendhart mentions 

 a method of checking the profuse bleeding 

 from leech-bites, which is simple and effec- 

 tual. The edges of the little wounds are 

 drawn together with a fine needle and 

 thread. The thread being drawn through 

 the cuticle only, gives no pain, and the 

 bleeding is at once suppressed. 



