TRANSACTIONS OF SECTION B. 633 



on tlie square diagram a horizontal line cutting the diagonal. Further, the compo- 

 sition at a summit point on the freezing-point curve is exactly that of the definite 

 solid separating out over that branch of the curve. Experimental examples of 

 these relationships are supplied, for example, by Roozeboom's work on the hydrates 

 of ferric chloride, Stortenbeker's work on iodine and chlorine, Heycock and 

 Neville's work on gold and aluminium, and the author's work ' on the freezing- 

 point curves for mixtures of organic substances. Two cases are specially referred 

 to : (a) where the freezing-point curve exhibits a branch that does not reach a 

 summit ; (6) where the two components form a compound that is dimorphous, and 

 the corresponding freezing-point curve exhibits two intermediate branches, the 

 one enveloping the other. Examples of case (a) are furnished by the freezing- 

 point curve for gold and aluminium, and, to a certain extent, by that for phenol 

 and urea.- Examples of case (6) are found in the freezing-point curve for iodine 

 and chlorine, and in that for phenol and ^-toluidine." 



2. A Contribution to the Constitution of Disaccharides. 

 By Thos. Purdie, F.R.S., and James C. Irvine, Ph.D., D.Sc. 



It is shown in a recent communication to the Chemical Society that tetra- 

 methyl n-methyl glucoside, obtained by the action of methyl iodide and silver oxide 

 on a-methyl glucoside, yields on hydrolysis a well-defined crystalline tetramethyl 

 glucose possessing the ordinary properties of an aldose. The reactions of this 

 substance prove that its unmethylated hydroxyl group is in the y position, and 

 direct evidence is thus obtained of the correctness of Fischer's formula for the 

 parent methyl glucoside. 



The authors have extended their experiments to the hydrolysable sugars, and 

 the present paper deals with the results obtained in the methylation of cane-sugar 

 and maltose. 



Methylation of Cane-sugar. 



An aqueous solution of cane-sugar was mixed with methyl alcohol and alkylated 

 as usual by the addition of silver oxide and methyl iodide. The product, which 

 was readily soluble in alcohol, was then treated as in the alkylation of methyl 

 glucoside, two further alkylations in alcoholic solution and one in methyl iodide 

 being necessarj' to complete the reaction. 



The alkylated cane-sugar is a viscid neutral syrup readily soluble in ether, 

 alcohol, or methyl iodide, and showing no action on Fehlin^-'s solution. 



The compound has not yet been obtained in a state of purity, but combustions of 

 the substance dried at 100° in a vacuum and methoxyl determinations by Zeisel's 

 method showed that the alkylation was practically complete. On hydrolysis, which 

 ■was effected by boiling with dilute hydrochloric acid, the initial dextro-rotation 

 though not inverted was much reduced, and the cane-sugar ether was resolved 

 into a mixture of methylated glucose and fructose. The former proved to be 

 identical with the tetramethyl glucose (m.p. 81°-84°) above referred to ; in one 

 experiment the compound crystallised spontaneously from the oily product of the 

 hydrolysis, whilst in other cases it was obtained only after fractional distillation 

 of this product, being then found in the higher boiling distillate. The more vola- 

 tile fractions, judging from their lower dextro-rotatory power, contained the 

 methylated fructose, but the substance did not crystallise, and it was found impos- 

 sible to effect a complete separation by vacuum distillation. 



At our suggestion, Mr. D. M. Paul undertook the preparation of tetramethyl 

 fructose from methyl fructoside, in the hope of establishing the identity of the 

 substance with the methylated fructose produced in the above hydrolysis. The 

 preparation yielded tetramethyl methyl fructoside as a colourless mobile oil 

 boiling at 132°-136° under 10 mm. pressure and having no action on Fehling's 

 solution. 



' Journal of the Chemical Society, 1903, 83, 814. - Loc. eit. ' Loc. cit. 



