/• '(f^emical Science, 



^ law, which, under penalty of confiscation, forbids the use of any 

 venomous substance, such as arsenic, zinc, lead, and other mineral 

 colours in the printing or dying of fabrics which are intended for 

 clothing, or may come in contact with the human body. Many 

 cutaneous affections, it is said, of which the cause has hitherto been 

 unknown, are occasioned by the absorption of deleterious dying 

 substances. — Nouveau Journal de Paris, 1828, p. 2. 



10. Method of preventing Milk from turning sour. — Put a spoon- 

 ful of wild horse-radish into a dish of milk ; the milk may then be 

 preserved sweet, either in the open air or in a cellar for several days, 

 whilst such as has not been so guarded, will become sour. 



1 1 . Infernal change in the Position of Particles in Solids. — If a cer- 

 tain quantity of the prismatic crystals of sulphate of nickel be enclosed 

 in a bottle and then exposed to the heat of the sun, it frequently 

 happens that though their external form is preserved, so that they 

 may be measured, yet if broken they are found formed of a multitude 

 of octoedral crystals with square bases. This change requires two 

 or three days. These crystals by analysis appeared to contain 2.93 

 parts per cent, less of water, than the prismatic salt containing 7 

 proportionals. This is another striking instance of the internal 

 motions of the particles of solid bodies. — Mitscherlich, Ann. de 

 Chimie, xxxviii. 65. 



§ II. Chemical Science. 



1 . Conducting Power of Metals for Electricity. — The following 

 are the results of M. Pouellet's researches on this subject, and are 

 highly interesting, especially as regards the effect of alloys on the 

 metals ; for even small quantities of foreign substances exert great 

 influence on the conducting power. The purity of the silver is ex- 

 pressed by the proportion of pure silver per cent, present in the 

 alloy ; the column of figures represents the conducting power : — 

 Silver of 98.6 ... 860 Red copper . . 224 



Red copper ... 738 Brass. ... 194 



Silver of 94.8 . . 656 Iron .... 121 



Fine gold .... 623 Gold of 18 car. fine 109 



Silver of 80 . , . 569 Platina ... 100 



M. Pouellet finds, 1. That the conducting power is very exactly 

 proportional to the section of the wires from the smallest diameter 

 to that of three lines : 2. That it is in the inverse ratio, not of the 

 length of the wire, but of the length increased by a constant quan- 

 tity X. This quantity X, unchangeable for various lengths of the 

 same wire, changes with the nature of the metal, and for each 

 metal is in the inverse ratio of the section of the wire. M. Pouellet 

 therefore believes that the conductibility is truly in the inverse 

 ratio of the length of the wires, provided that the resistance opposed 



