182 Foreiii:n Literature and Science. 



'& 



A memoir of Luiscius, (Rotterdam, 1798,) on the putre- 

 faction of vegetable and animal substances, states, 1st, that 

 these substances, in contact with water, are entirely decom- 

 posed, if the air have free access; 2d, that the decomposi- 

 tion is singularly accelerated by air ; 3d, that under those 

 circumstances, (air and water having free access,) much ni- 

 tric acid is produced, and a little ammonia ; 4th, that these 

 substances putrefy in different times in the following order ; 

 urea, gluten, animal gelatine, muscular fibre, starch, white of 

 eggs, gum, sugar, vegetable fibre, (fcc. — Ibid. 



27. Presence of ammonia in argillaceous minerals. — It is 

 the conclusion of M. Bouis, of Perpignan, from his experi- 

 ments and researches, that the argillaceous odor of miner- 

 als is owing to the presence of ammonia. He has found it in 

 pipe clay, impure gypsum of various formations, steatitic 

 earths, anterior to the presence of organised bodies, &c. 

 When these substances are moistened with a solution of 

 caustic potash, the argillaceous odor is generally increased, 

 and in that case a glass wet with hydro-chloric acid occa- 

 sions white vapors when held near them. Litmus paper, 

 slightly reddened, and placed over these earths, thus moist- 

 ened, has its blue color restored. 



Argillaceous odor has been generally ascribed to the ox- 

 ide of iron, but it is difficult to conceive how this substance 

 can render mert substances odorous. The presence of am- 

 monia in these minerals may account for the odor they give 

 out on being breathed upon, or slightly moistened. The 

 ammonia becomes the vehicle of the peculiar argillaceous 

 material. 



An analogous phenomenon occurs in musk, tobacco, &c. 

 which when perfectly dry, are almost inodorous but when 

 moistened with a weak solution of ammonia, give out their 

 characteristic odor. — Ibid. 



28. Magnetism. — M. Scebeck, in making new researches 

 on the property which the metals have of diminishing the 

 number of oscillations of the magnetised needle, determined 

 the different degrees of this force in each metal. He used 

 a needle two and one eighth inches long, suspended by a fibre 

 of silk, at the distance of three lines over metallic plates 

 and observed that between the two amplitudes of 45° and 

 10° it made 



