78 REPORTS ON THE STATE OF SCIENCE.—1917. 
transparent gels, which, however, are so brittle that they can be pulverised 
between the fingers into innumerable minute angular particles which do 
not coalesce. 
These insoluble gums are not at present of any value, the chief interest 
in them commercially centring round the possibility of converting them 
into soluble products. Several patents have been taken out with the 
view of converting such gums into colloid sols, other colloidal products 
being also mentioned. Thus L. Kern (Eng. Pat. 21,370, 1891) purposes 
to render cherry, peach, and other gums soluble by heating with water 
under pressure; F. Fritsche (Eng. Pat. 1,353, 1908) prepares soluble gums 
by acting upon the products obtained from alge and lichens—carrageen 
moss, agar, Iceland moss, &c.—Hast India gum, bassorine, &c., with 
sodium perborate after boiling with water under pressure; A. Bcidin 
(Eng. Pat. 16,589, 1905) proposes to render starch, inulin, glycogen, 
gelose from agar-agar, gums and mucilages more readily soluble, by con- 
verting the phosphates which they contain into insoluble phosphates 
by addition of metallic salts or into monobasic acid salts by acidifying. 
Vegetable Mucilages. 
A variety of vegetable mucilages can be prepared by treating seeds, 
roots, &¢., of various plants with water. These products, which were 
investigated many years ago by Fremy, Mulder, Chodnew, &c., were 
known as pectins or pectinous substances. Our knowledge of these 
materials needs revision. They are more nearly related to gum arabic 
than to the hemicelluloses. Pectose was the soluble colloidal material 
contained in beetroot ; this was converted by means of an enzyme or 
ferment called pectase into pectin and subsequently into pectic acid, 
coagulation not occurring except in presence of CaO or a salt of Ca, Ba, or 
Sr. The coagulated mass is not pectic acid but a pectate of one of the 
alkaline earths (A. Mallevre, ‘ Bull. Soc. Chem.’ 1895, 18, 77-82). This 
looks like adsorption compounds. 
The gelatinous material pectose is present in the pulp of ripe fruits, 
such as apples or pears, and in roots, e.g., carrots and beetroot, in association 
with cellulose. It is insoluble in water (Fremy). By the action of the 
ferment pectase, or acids, alkalies, or milk of lime, pectose is converted 
into pectin or pectic acid; in’ other words, it is converted into a sol. 
Pectin is contained in the juice of ripe fruits, from which it is pre- 
cipitated by alcohol in presence of HCl. It is soluble in water and is 
precipitated from the solution by basic lead acetate, also by Ba(OH), 
and Ca(OH), in excess, but not by NH,HO, NaHO, HCl, H,BO, or 
borax. On boiling an aqueous solution of pectin it becomes insoluble, 
being converted into parapectin (Fremy, Sidersky), parapectic acid 
( Watts’ Dict.,’ vol. 4, p. 365), metapectic acid (J. Weisberg, ‘ Chem. 
Zeit.’ 18, 2). Parapectin is converted by dilute acids and bases into 
metapectin, and with concentrated solutions of the same into’ para- 
pectic acid. Metapectic acid has an acid reaction; it is completely 
precipitated by lime and basic lead acetate. On prolonged heating it 
is converted into metapectic acid (J. Weisberg, ‘Chem. Zeit.’ 18, 2). 
Pectous or pectosic acid is obtained by the action of pectase upon a solution 
of pectin, also produced by the action of cold solutions of the alkalies 
upon the same substances. It is a gelatinous substance, slightly soluble 
