170 Miscellaneous Intelligence. 



said to be very moderate ; and it is further stated to be the only 

 process at present known, not even excepting sinking, which effec- 

 tually destroys the white ant. 



13. Preservation of Butter. — M. Thenard recommends the method 

 used by the Tartars, which consists in fuzing the butter in a water- 

 bath at a temperature of 190° F., 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 crystallize, 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 was on the first day, especially if the upper 

 part be excepted. 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, according to M. Thenard, be removed almost 

 entirely by similar meltings and coolings. — Bull. Univ. D. xii. 155. 



14. On the Dilatation of Stone, by M. Destigny (from the Memoire 

 de la Soc. libre ctEmul. de Rouen.) — The phenomena of dilatation by 

 heat have been long known, and have been determined for a certain 

 number of bodies. M. Destigny has extended this determination 

 to the dilatation of stones observed by Bouguer in Peru, for bricks ; 

 by George Juan, a Spaniard, quoted by M. Rondelet {Treatise on 

 the Art of Building) ; and lastly, by M. Vicat, at the hewn stone 

 bridge of Souillac. The precise extent of this dilatation was unknown. 

 To obtain it, an instrument of extreme delicacy was required, and 

 M. Destigny himself constructed one, founded upon the difference 

 of dilatation of stone and iron, or copper. He selected for his 

 experiments stones about 365 millimeters in length, 165 broad, 

 and 50 thick, and fixed at one end a metallic rod, by means of a 

 foot fixed in a copper plug let into the stone, while the other end 

 of the rod rested against the small arm of a very sensible lever, 

 which moved a needle indicating the difference of dilatation. This 

 small arm was 3^- mm. long, the other 100 mm. This last moved 

 another lever, the length of the arms of which was 3 mm. for that 

 against which it rested, and 100 mm. for the other, which was de- 

 signed to point out on the arc of a circle, with a radius of 100 mm., 

 the progress of the dilatation. The ratio of the space described 

 between the small arm of the first lever, and the great arm of the 

 second, was therefore as 1 : 1000. Transferring, then, the whole 

 apparatus to a stove heated to 40, the dilatation must take place ; 

 and if it were the same for the stone and the metallic rod, the 

 instrument would have indicated nothing; but the iron or the 

 copper, having a much greater dilatation, put the small arm of the 

 first lever in motion, and the amount of the difference of the dila- 

 tation might be read off on the arc of the circle. M. Destigny has 

 thus found, for example, in one of his first experiments, the needle 

 indicating 231,84 mm. 



