TRANSACTIONS OF THE SECTIONS. 79 



quately expressed ty means of tie following table of rational formulas *, wliere 

 the non-essential constituents are separated from the essential constituents by a 

 horizontal line : — 



Glycolic alcohol. 20^; H^ 0,i 2H, C,; H, O, 



Deglycolic alcohol. 20^ ; H, U,i 2C j H^ 0^ 

 H,C,0, H,0,. H,0, . 



Glycohte of water. 20,; H,0,; 2Hj 2C,0 ~ 



H,C,0,, H,0,. 11,0,. 



Glycolate of water. 20,; H,0,i 2Hj 20,0, 

 H,C„0,„ H,0, . H,0,. 



Oxyg-lycolate oi water. 20,; H.,0,i 2H; 20. 



So far as the author Imows, the glycolic alcohol, which is the parent molecule 

 of this family gi'oup, has not yet been obtained in a state of isolation. The ethy- 

 len-glycol might at first sight be taken for the missing alcohol, more particularly 

 when we couple the decidedly biatomic character of their respective molecules 

 with the other, and even more significant fact, that the whole of the glycolic he- 

 terologues may be produced by the simple oxidation of the ethylen-glycol. Never- 

 theless, and notwithstanding these striking points of resemblance, the author is in- 

 clined to believe that these two alcohols are only isomeric ; and he gi'ounds this be- 

 lief upon the occurrence of a certain class of chemical compounds, among which 

 the so-called diethyl -acetal is the most conspicuous and best investigated member. 

 This diethyl-acetal is sti-ictly isomeric with the diethyl-ether of the ethylen- 

 glycol, and it is no doubt the missing glj'colic alcohol to which we are indebted 

 for this curious and instructive case of isomerism. A cursory examination and 

 comparison of the subjoined rational fonnulse will suffice in order to prove the 

 correctness of this view. 



H 0,0, H,0,. H,0,. 



Ethylen-glycol. 2H, 0, ; H, 0,^20,; H, 0, 



H„0,0, H,0,. H,0,. 



Glycolic alcohol. 20, ; H,"0,i 2H, 0, ; H, O, 



^. , , H..C 2H,0j'H,0,. 2H,0,;H,0, 



Diethyl-ether of ethylen-glycol. 2H, 0., ; H., 0,-20, ; H„ O, 



H„ C„ O, 2H,C,;H,0,. 2H;0, ; H, O, 



Diethyl-acetal. 20, ; H, O^i 2H, 0, ; H, O, 



Ethylen-glycol differs from glycolic alcohol in two essential points : — First, in 

 the former compoimd the two alcoholic constituents are represented as playing 

 the coordinate part of principal alcoholic bases, while in the latter compound one 

 of these alcoholic bases is represented as playing the subordinate part of adjunct 

 to the other base. Secondly, the relative positions which the two alcoholic con- 

 stituents occupy in ethylen-glycol are exactly reversed in the glycolic alcohol, A 

 mere glance at the two formulae which express the chemical constitution of the 

 isomeric ether derivatives will enable the reader to complete the analysis of these 

 hitherto obscure and unintelligible cases of isomerism. To the second member in 

 the family of glycolic heterologues, which is likewise very little known, the author 

 has applied the term "deglycolic alcohol," in order to record the fact that it is 

 produced from the primary alcohol by the simple abstraction of two molecules ox 

 hydrogen from the methylen adjunct of the principal water-base. This secondary 

 alcohol, like the majority of the alcohols which occupy the second place in the 



* The following are some of the typical symbols of molecular grouping used in these 

 formulte : a dot connects the base with its acid, a semicolon the hydrocarbon adjunct with 

 its principal, an inverted semicolon the halogen (acid, base, or salt) adjunct with its prin- 

 cipal, and a concave curye two principal bases with one another — 



H,=2; C,= 12; 0,=16. 



