490 IfUelligence aiid Miscellatieous Articles, 



impossible that this salt might exhibit phaenomena of decomposition 

 of the same class as the singular ones which M. Thenard observed 

 with binoxide of hydrogen. In fact this is the case ; many sub- 

 stances which decompose binoxide of hydrogen, without either ac- 

 quiring or losing anything, also decompose the nitrosulphates. 

 Spongy platina, oxide of silver, metallic silver, powdered charcoal, 

 and oxide of manganese, produce this effect -, the two first-men- 

 tioned especially act with extreme rapidity upon the nitrosulphate 

 of ammonia. 



*' I convinced myself," continues M. Pelouze, " that this remark- 

 able phgenomenon was due, as in the case of binoxide of hydrogen, 

 to an action of presence [a une action de presence], and that it never 

 produces more than a mere conversion of nitrosulphate of ammonia 

 into protoxide of azote and sulphate of ammonia. Oxide of silver 

 is not reduced, for if it be washed after having caused it to decora- 

 pose a large quantity of this salt, it afterwards dissolves in nitric 

 acid without the disengagement of red vapours." 



M. Pelouze afterwards remarks that " it would be very difficult to 

 discover the probable cause of these singular phaenomena ; but the 

 verycircumstanceoftheirbeingatpresentinexplicable, they appeared 

 to me the more to merit the attention of chemists. What indeed 

 is more calculated to excite curiosity than to observe a salt, by the 

 mere contact of a body which neither yields anything to nor takes 

 anything from it, decompose with extreme rapidity into new forms, 

 among which the agent producing these violent actions remains 

 chemically passive? 



" Two compounds, namely, binoxide of hydrogen and hydruret 

 of sulphur, are already known as possessing the property of decom- 

 posing by the influence of a simple action of presence." 



Ann. de Ch. et de Phys., Ix. 158. 



CATALYSIS. — ACTION OF PRESENCE. 



In the 61st volume of the Ann. de Ch. et de Phys., Berzelius has 

 followed up the remarks of Pelouze on the action of 'presence^ and 

 has given to it the name of Catalysis. His notice on this subject is 

 entitled, '^ Some ideas on a new force acting in the combinations of 

 Organic Compounds." 



In inorganic nature, new combinations are formed between the 

 different bodies which are present, because these bodies have a 

 greater tendency to combine with each other than with other bodies. 

 Those bodies which have a great affinity for each other, combine 

 together, and reject those for which they have a weaker affinity, and 

 with which they were previously combined, and these also combine 

 together. Until the year 1800, this tendency of bodies to unite 

 was the only one known, except heat, and in some cases lights that 

 could effect their combination. The influence of electricity was of 

 later discovery, but it was soon also discovered the chemical and 

 electrical affinity were the same, and that heat and light acted only 

 by increasing or diminishing these affinities. On proceeding to the 

 study of orgamc chemistry, very different bodies were obtained 

 from the same crude material by different organs. In animals, this 



