VII] FATS AND ALLIED SUBSTANCES 91 



Cruciferae : Garden Cress (Lepidium sativum) 25 "/o : Black Mustard 

 (Sinapis nigra) 20 7o : White Mustard {Sinapis alba) 25 7o : Colza 

 (Brassica rapa var. oleifera) 33 7o : Rape (Brassica napus) 42 Yo- 



Rosaceae : Almond {Prunus Amygdalus) 42 7o '- Peach (P. Persica) 

 35 Vo : Cherry (P. Gerasus) 35 Vo ; Plum (P. domestica) 27 7„. 



Linaceae : Flax (Linum usitatissimum) 20-40 °/o- 



Euphorbiaceae : Castor-oil (Ricinus communis) 51 Vo* 



Malvaceae: Cotton {Gossypium herhaceum) 24%- 



Sterculiaceae : Cocoa (Theobroma Gacao) 54 Yo- 



Lecy thidaceae : Brazil Nut (Bertholletia excelsa) 68 "/o- 



Oleaceae: OMve {Glea euroimea) 20-1 0^1 q-. Ash (Fraooinus excelsior) 

 27%. 



Rubiaceae: Coffee (Goffea arabica) 12*'/o- 



Cucurbitaceae: Pumpkin (Gucurbita Pepo) 41 °/o- 



Compositae: Sunflower {Helianthus annuus) 38 "/o- 



The conclusion must not be drawn from the above list that the seeds 

 of the plants mentioned have exclusively fats as reserve materials. In 

 many cases fat may be the chief reserve product, but in others it may 

 be accompanied by either starch or protein or both. 



Some of the best-known examples of fat-containing seeds which yield 

 "oils" of great importance in commerce, medicine, etc., are Ricinus 

 (castor oil), Brassica (colza oil), Gossypium (cotton-seed oil), Gocos 

 (coconut oil), Elaeis (palm oil), Glea (olive oil). 



In the plant the fats are present as globules in the cells of the fat- 

 containing tissues. 



Plant fats may vary from liquids, through soft solids, to wax-like 

 solids which generally have low melting-points. They float upon water 

 in which they are insoluble. They are soluble in ether, petrol ether, 

 benzene, chloroform, carbon tetrachloride, carbon bisulphide, etc.: some 

 are soluble in alcohol. With osmic acid fats give a black colour, and they 

 turn red with Alkanet pigment which they take into solution. 



Expt. 90. Tests for fats. Weigh out 50 gms. of Linseed {Linum usitatissimum) 

 and grind in a cofFee-mill. Put the linseed meal into a flask, cover with ether, cork 

 and allow the mixture to stand for 2-12 hrs. Filter off the ether into a flask, fit with 

 a condenser and distil off the ether over an electric heater. (If a heater is not avail- 

 able, distil from a water-bath of boiling water after the flame has been turned out.) 

 When the bulk of the ether is distilled off", pour the residue into an evaporating dish 

 on a water-bath and drive off the rest of the ether. With the residue make the 

 following tests in test-tubes : 



(a) Try the solubilities of the oil in water, petrol ether, alcohol and chloroform 

 It is insoluble in water and alcohol, but soluble in petrol ether and chloroform. 



