668 REPORT— 1892. 



alcohol contair.8 C^II^-O, and if from two molecules of alcohol one molecule of water 

 is subtracted a molecule of ether results : '2G^JI,.0 - OH, + C^Hj^O. As sulphuric 

 acid is known to have a great attraction for water, it is easy to imagine that the 

 acid combines with the water and ether passes oif. But it is found that a small 

 quantity of sulphuric acid at the temperature of 140°-150° will transform a very- 

 large amount of alcohol into ether and water, much more than can be explained by 

 assuming that the acid has combined with the water. If a mixture of sulphuric 

 acid and alcohol is heated to a temperature of 140°-150°, and alcohol allowed to 

 flow into the liquid, a mixture of ether and water vapours passes over, and after a 

 large quantity of alcohol has been transformed the amount of sulphuric acid is 

 found to be unaltered. At first glance this seems very difficult to explain, but on 

 further investigation it is found that alcohol and sulphuric acid act one on another 

 to form ethyl-sulphuric or sulphovinic acid — 



SO,Ho, + EtHo = SO.IIoEto + OH,. 



But when ethyl-sulphuric acid is heated with alcoliol ether is formed with the 

 reproduction of sulphuric acid — 



SOalloEto + EtHo = OEt, + SO.Hoo. 



The sulphuric acid is then able to produce ethyl-sulphuric acid by acting on more 

 alcohol, so a continuous production of ether and water takes place without loss of 

 sulphuric acid. Another well-known action is the combination of oxygen and 

 hydrogen under the influence of spongy platinum. In this case the platinum 

 remains apparently unaltered, and is capable of causing the combination of any 

 quantity of mixed gases. As spongy platinum possesses the power of absorbing 

 large quantities of gases it is usually said that the molecules of oxygen and hydro- 

 gen are so much condensed in the platinum that they are brought within the 

 sphere of each other's attractions, and consequently combine. 



Another instance of an action of this kind is atibrded by the oxidation of 

 ammonia in the presence of chromic oxide. When ammonic dichromate is heated 

 an evolution of gas occurs, and a residue of chromic oxide is left which bears a 

 striking resemblance to a mixture of black and green tea ; when some of this sub- 

 stance is placed on a piece of wii'e gauze, heated and then supported over a vessel 

 containing a strong solution of ammonia, the oxide glows, in a manner similar to 

 the glo^wing of spongy platinum under the influence of a mixture of hydrogen and 

 air. Under the.'^e conditions the chromic oxide facilitates the oxidation of the 

 ammonia, but it becomes changed during the process ; instead of having the appear- 

 ance above described it acquires a bright-green colour. Now, we loiow that 

 chromium is capable of forming several combinations with oxygen. Is it therefore 

 too much to suppose that the chromium is alternately oxidised by the oxygen of 

 the air, and reduced by the hydrogen of the ammonia, so that, although in the end 

 it has the same composition as at the beginning, nevertheless it has been con- 

 tinuously decomposed and reproduced? Now, may not a similar change take place 

 during the action of spongy platinum on a mixture of hydrogen and oxygen ? The 

 alteration of the platinum is very slight, but I believe I have observed a slight 

 modification of the appearance of a fragment of spongy platinum that was kept 

 glowing by a small jet of purified hydrogen for some hours ; the gas not being 

 allowed to burn so as to heat the platinum to a very high temperature, the metal 

 appears to be compacted and to be covered by minute spherules of glistening metal. 

 Now, may not the platinum have entered into combination with one or other of 

 the gases and been subsequently reduced ? If this is the true explanation then we 

 have in this case a continuous series of chemical changes and the ' catalysis ' is 

 explained. 



We all know the ease with which oxygen is obtained from potassic chlorate 

 when heated with a small quantity of oxide of manganese: the quantity of peroxide 

 is the same at the end of the process as at the beginning, and it may be used over 

 and over again to assist in the decomposition of fresh potassic chlorate. The oxide 



