Oxidation of Carotin. 189 



when distilled yielded appreciable quantities of formaldehyde, but 

 no trace of reducing sugar was formed. 



The quantitative weighings of dry films during oxidation indi- 

 cated that further oxidization is possible after the carotin has been 

 bleached white. 



The presence of an oxidase strongly accelerates the oxidation of 

 carotin both in light and in darkness. A solution of carotin in hot 

 alcohol was poured into water so as to form a yellow turbid emul- 

 sion. This was divided into four parts, A, B, C, D. To A and C 

 a few drops of a solution of copper sulphate and salt were added, 

 which acts as a strong oxidase. A and B were exposed to sunlight, 

 C and D were kept in darkness in beakers with a large free surface 

 exposed to air. In A and C the emulsion, owing to some mechani- 

 cal action of the copper sulphate, aggregates to larger particles, 

 which would tend to delay oxidation, but nevertheless A was fully 

 bleached in two days, B in four days, C in six days, and D even 

 after eight days was still reddish yellow, but somewhat paler. A 

 yielded a distinct trace, B a doubtful trace, and C and D no trace 

 of formaldehyde on distilling. 



A curious result was given by a carotin solution obtained by 

 boiling the expressed juice of grated carrots, washing the floating- 

 red mass with absolute alcohol, dissolving in hot absolute alcohol 

 and separating with petrol ether. Emulsions were made by evapo- 

 rating to dryness, dissolving in absolute alcohol, and adding- 

 water. Repeating as above, the oxidized liquids were fil- 

 tered, evaporated to dryness, and the residue digested with cold 

 water for twenty-four hours, filtered, and then tested for reducing 

 hexose sugars. A gave strong positive results, B weak positive 

 results, C fairly strong positive tests, and D doubtful or negative 

 tests. 



The appearance was given as though the addition of a metallic 

 oxidase caused carotin to oxidize to carbohydrates. The solutions 

 used, however, contained carotinoids as well as carotin, and carotin 

 purified by precipitation did not yield any sugar on oxidation 

 under any conditions. 



From the original alcoholic carotinoid solution sugar sepa- 

 rated, when it was treated with alcoholic potash. The liquid A and 

 C after oxidation filtered clear, whereas B and D filtered turbid, and 

 left waxy residues, which apparently held sugar as a physical mix- 

 ture or in loose chemical union, and from which even long contact 

 with cold water removed the sugar only to a slight extent or not at 

 all. Hence the apparent production of sugar on photo-oxidation 

 in the presence of copper sulphate and salt. 



