Prof. Wanklyn on Limited Oxidation. 541 



capable of even momentary resistance to the action of dilute chro- 

 mic acid, it would have been preserved. It is worthy of remark 

 that so successful was the effort to obtain the most complex fatty 

 acid which could result, that the butyric acid actually obtained 

 appears to be pst-udo-butylic acid. 



These examples will serve to give an idea of the state of our 

 knowledge of the oxidation-process up to the present day. 



Before proceeding to describe the immense improvement which 

 has been made by Chapman and Thorp in the conduct of the 

 oxidation-process, it is only right to call attention to my own 

 oxidation of the propione got from carbonic oxide and sodium- 

 ethyle. Having totally failed to oxidize propione by distilling 

 it in an open retort with bichromate of potash and dilute sul- 

 phuric acid, I sealed it up with excess of bichromate of potash 

 and dilute sulphuric acid, and heated for many hours in the 

 water-bath. The propione slowly disappeared, but, in spite of 

 the prolonged action of the dilute chromic acid, no carbonic acid 

 made its appearance ; and after the termination of the experiment, 

 propionic as well as acetic acid was found in the tube. This 

 result, by which the extreme persistence of propionic and acetic 

 acids was established, is the germ which, in the hands of my 

 friends Chapman and Thorp, has developed so magnificently. 

 Chapman and Thorp have shown that, although strong chromic 

 acid, as is well known, performs an utter oxidation down to car- 

 bonic acid and water, yet dilute chromic acid behaves absolutely 

 differently. The current notion of the oxidation -process is ap- 

 plicable to strong chromic acid, but not to dilute chromic acid. 

 In an aqueous solution of 8 per cent, of bichromate of potash 

 with just enough sulphuric acid to decompose it completely, che- 

 mists are furnished with a reagent which is absolutely without 

 action on the acids of the fatty series at temperatures below 

 100° C. An exception is made for formic acid, which, as has 

 often been remarked, is not a characteristic member of the fatty 

 series. 



Not only are the fatty acids unattackable when ready formed, 

 but they are unattackable when nascent. And besides the acids 

 of the fatty series, and benzoic acid and perhaps its homologues, 

 organic chemistry hardly includes a compound which is capable 

 of resistance to the prolonged action of this normal solution of 

 chromic acid. It is hardly possible to overrate the importance or 

 this discovery of Chapman and Thorp. Before it all the crude- 

 ness and want of precision vanishes from the oxidation-process. 

 We have a second order of combustion — a u limited oxidation " — 

 wherein the place of carbonic acid and water is supplied by the 

 different fatty acids which figure as ultimate products, as unal- 

 terable by the oxidation -agent used as are carbonic acid and 

 water by excess of oxygen at a red heat. 



