PROPERTIES OF THE SUGAR OF MILK. 559 



changed into butter oil, and into one or other of those fatty acic s which 

 are present in butter in smaller quantity. 



3°. Margaric acid. — When this fat (Margarine) is introduced into a 

 hot solution of caustic potash, it readily dissolves and forms a soap. If 

 the solution of this soap in water be decomposed by the addition of diluted 

 sulphuric acid a white fatty substance separates, which, after being col- 

 lected, dried, and dissolved in hot alcohol, crystallizes as the solution 

 cools, in the form of pearly scales. This substance is known by the 

 name of the margaric (or pearly) acid. Margarine consists of this acid 

 in combination with a sweet substance known by the name of glycerine, 

 or oil sugar,* 



Margaric acid is represented by the formula 34 C + 34 H + 4 O, or 

 C34 H34 O4. To this formula it will be necessary in a few minutes to 

 revert. 



Butter oil. — The liquid fat expressed from butter has the appearance 

 of an oil, sometimes colourless, but often tinged of a yellow colour. It 

 has the taste and smell of butter — mixes readily with alcohol, and be- 

 comes solid when cooled down to 32 '^ F. — the freezing point of water. 

 It dissolves without difficulty in a solution of caustic potash, and forms 

 a soap. 



Acid of bulter-oil — oleic acid of butter. — When the solution of the oil 

 in caustic potash is diluted with much water, and decomposed by the ad- 

 dition of diluted sulphuric acid, an oily substance is separated, which is 

 different from the original oil of butter, possesses acid properties, and is 

 known by the name of the oleic acid of butter. This fatty acid has 

 never hitherto been obtained from any other substance than the oil of 

 butter, and the oil consists of the acid in combination with oil-sugar. 

 You will recollect that margarine consists of margaric acid in combination 

 with the same sugar (p. 558.) 



* Such is the apparent composition of the two fatty substances, margarine and butter-oil, 



inasmuch as when they are dissolved in a solution of caustic potash, and their solutions 



afterwards decomposed by an acid, tlioy are resolved respectively — 

 Margarine — into margaric acid and oil-sugar ; 

 Butter- oil— into butter oleic acid and oil-sugar. 

 But, for the benefit of my chemical readers (my other readers will please to pass ovct 



this note), it is necessary to state- 

 to. That a compound is supposed to exist, consisting of 3 atoms of carbon united to 2 o 



hydrogen— Cii H:^, to which the name odipyle is given. 

 2°. That this radical Cs H2 unites with an atom of oxygen, forming C3 H2 O, or oxide of 



3°. That in neutral fatty bodies, such as margarine, this oxide exists in combination 

 with a fatty acid. Thus, for example, that— 



, _ . , f S 1 of margaric acid = C34 H34 O4 



Mcrganne consists ofji ^f ^^.^% ^f ,ipy,g = C3 Ha O 



Forming, together, 1 of margarine =:C37H36 05 



And r ,.„., „f SI of oleic acid of butter = C34 H31 05 



butter-otl of J J ^f ^^.^^ ^f lipy,g = C3 H2 O 



Forming, together, 1 of butter-oil = C37 H33 Os 



4°. And that when this oxide of lipyle is separated from its combination with the fatty 

 acids it unites with a quantity of water, and forms glycerine or oil-sugar. Thus— 



2 of oxide of lipyle = Ce H4 O2 united to 



3 of water = H3 O3 give 



1 of glycerine (oil-sugar) . . • . . . . =: Ce H? O5 

 5". The above is the view of Berzelius, but Redtenbacher has recently suggested, [Annai! 

 der Chem. und Phar, XLVII., p. 141,] that a known substancF palled acrolein exists in the 



