790 



SCIENCE. 



[N. S. Vol. VII. 180. No. 



cause which is operating. A very small 

 amount of a foreign substance, which ap- 

 parently did not enter into the reaction, 

 was found to be capable of increasing the 

 velocity of a reaction to a very great ex- 

 tent. Examples of such reactions have long 

 been known ; indeed, the transformation 

 of starch into sugar by boiling with acids, 

 has been known for more than a century. 

 Such action on the part of a foreign sub- 

 stance was termed by Mitscherlich and 

 by Berzelius ' catalytic' Such effects have 

 recently been classed under the general head 

 of chajiges in the reaction velocity. 



Two experiments were then performed 

 illustrating both acceleration and retarda- 

 tion of reaction velocity. If to a dilute 

 solution of potassium iodide an equivalent 

 of potassium bromate and acetic acid is 

 added, free iodine will separate very slowly, 

 and this can be made visible by the pres- 

 ence of a little starch. If a drop of a so- 

 lution of potassium bichromate or ferrous 

 sulphate is added, the solution becomes 

 blue in a few moments, showing an accel- 

 eration in the velocity of the reaction. 

 The bichromate does not act as an oxidiz- 

 ing agent under these conditions, as can be 

 shown by removing the iodine by means of 

 sodium thiosulphate, when the solution 

 will have the yellow color of the unreduced 

 bichromate. Further, ferrous sulphate, 

 which produces the same reaction, is a 

 strong reducing agent. 



The retardation of the velocity of reaction 

 was shown as follows : When an acid is 

 added to a dilute solution of sodium thio- 

 sulphate the solution becomes cloudy, after 

 a time. The addition of sulphurous acid 

 causes the solution to remain clear for a 

 much longer time. This is probably not 

 catalysis in the strict sense, but the action 

 of mass. Yet there are cases known where 

 the retardation is undoubtedly a catalytic 

 action, but these are less suitable for the 

 purpose of demonstration. 



We have, then, in small amounts of cata- 

 lyzers, a means of increasing or diminishing 

 the velocity of reactions a thousand or a 

 million times. Says Ostwald : " I should 

 like to express my conviction that it is 

 difficult to overestimate the importance of 

 this for organic life." 



But what may be the technical signifi- 

 cance of catalytic action ? To increase the 

 velocity of machines a proportionally larger 

 amount of work must be done. An express 

 train carrying the same weight as a freight, 

 but moving with greater velocity, will con- 

 sume more coal in traveling the same dis- 

 tance. A galvanic cell will work more 

 economically the smaller the strength of 

 current. Also in the other technical fields 

 velocity is secured at the expense of energy. 



Only in chemcal processes is this avoided. 

 The addition of a small amount of a cata- 

 lyzer, which is not used up in the reaction, 

 majr enormouslj^ increase the velocity of a 

 reaction. 



The significance of this for the industries 

 becomes apparent, when we consider how 

 important is the element of time in carry- 

 ing out technical processes. Could a cata- 

 lyzer be found for such processes a factory 

 using the same amount of machinery or 

 apparatus could increase its productivity 

 many fold, and thus save interest on capi- 

 tal invested ; or a train could greatly in- 

 crease its velocity with the same consump- 

 tion of coal. 



As a matter of fact, catalyzers have long 

 been used in some of the industries, such as 

 the manufacture of sulphuric acid, dyeing, 

 bleaching, etc. But up to the present this 

 has been purely empirical, and frequently 

 the role played by the catalyzer has not 

 been recognized. The intelligent applica- 

 tion of catalytic processes to the industries 

 has recently been begun, and this is en- 

 tirely due to the scientific study of such 

 processes. 



" I regard the field of catalytic phenom- 



