480 
added, whilst the other was left as it is; in a short time, more 
silver was deposited in the tube containing glucose, though a neutral 
solution of glucose cannot reduce silver nitrate. This is another case 
of an induced reaction already studied. (Dhar, Trans. Chem. Soc. 
1917, 111 , 690). 
Summary: a. The reaction between silver nitrate and ferrous 
ammonium in dilute Solutions is bimolecular. The reaction is very 
rapid even at 0° and the temperature coëfficiënt has a small value. 
h. When the Chemical change has proceeded up to a certain 
extent, an equilibrium is set up: 
Ag + Fe (NO,), ^ AgNO, + Fe (NO,), 
c. Acids accelerate this change; in case of nitric, sulphuric, citric, 
tartaric acetic acids, the greater the concentration of H' ions, the 
greater is the acceleration. Carbonic acid markedly accelerates, whilst 
boric acid and phenol are without action. Manganese sulphate and 
potassium nitrate are retarders. 
d. A neutral solution of glucose cannot reduce silver nitrate at 
about 20°; the reaction between ferrous ammonium sulphate and 
silver nitrate induces the Chemical change between glucose and 
silver nitrate. 
b. Oxidation oj sodium sulphite by atmospheric oxygen. 
Luther (Zeit. phys. Chem. 1903, 45 , 662) advanced the idea that 
negative catalysis cannot take place in a reaction which is entirely 
free from positive catalysts and the phenomenon is really due to 
the destruction or otherwise rendering latent of these positive catalysts. 
Titoff (ibid. 1903, 45 , 641) as a result of his studies of the combined 
effect of positive and negative catalysors on the rate of oxidation of 
sodium sulphite lends his support to Luther’s theory. The effect of 
negative catalysts on this reaction was first studied by Bigelow (ibid. 
J898, 26 , 493) who found the oxidation of the salt in aqueous 
solution to be greatly retarded by the presence of minute qüantities 
of benzaldehyde, iso-butyl alcohol, glycerol, phenol etc. Bigelow also 
demonstrated that the effect of negative catalyst is not on the rate 
of solution of oxygen, but on the rate of the reaction between the 
sulphite and oxygen. A few years later.TiTOFF substantiated Bigelow’s 
results and in addition studied the simultaneous effect produced by 
copper sulphate, a powerful accelerator and manitol a strong retarder. 
He found that these two substances do not exert any additive effect 
but influence each other. Young (Jour. Amer. Chem. Soc. 1901, 23 , 
119; 24 , 1902, 297) found that small qüantities of certain alkaloids 
