Leaves in Autumn. 273 



the name of chlorophyle, among the immediate products of the 

 vegetable kingdom. This substance appearing to be the seat of 

 the modifications which take place in the colour of the leaves, it 

 was necessary for me to submit it to examination. After exa- 

 mining anew the properties which it possesses, I set myself to 

 examine the corresponding substance of the leaves coloured yel- 

 low and red by the autumnal influence. To obtain the chloro- 

 phyle, MM. Pelletier and Cavantou employed alcohol acting 

 upon the substance of plants ; but I found that when leaves 

 were to be operated upon, it was necessary to boil them previ- 

 ously in ether, to remove the wax and oily matters which they 

 almost always contain. On treating yellowed leaves of the pop- 

 lar (Populus J'astigiatd)^ with boiling sulphuric ether, it was 

 slightly coloured yellow, and deposited, on cooling, a pulveru- 

 lent substance, having all the properties of wax. By evapora- 

 tion, there was obtained a white, solid, fat matter, fusible at a 

 low heat, of a strong poplar smell, and exhaling an acrid and 

 pungent vapour when heated. This substance is equally found 

 in the green leaves. The residuum of the yellow leaves was 

 boiled in a sufficient quantity of alcohol at 40°, which was tinged 

 of a beautiful yellow hue, and the leaves lost their colour. This 

 alcoholic solution, on being mixed with water, does not at first 

 render it turbid ; but there presently separate yellowish flakes 

 of a resinous appearance. If, after mixing it with a little solu- 

 tion of alum, there is added pure potash, a beautiful lac of an 

 orange colour is precipitated. Evaporated at a gentle heat, the 

 alcoholic solution of the yellow leaves deposits a solid substance 

 of an orange-yellow colour, and herbaceous taste, translucid, be- 

 coming agglutinated together when warm ; soluble in ether and 

 alcohol, which it colours yellow, insoluble in cold water, and 

 dissolving a little with the aid of heat in diluted acids. When 

 acted upon by fire, it melts and bubbles, then emits a pleasant 

 smell, like that of burnt vegetable matter. Heated in diluted 

 nitric acid, the yellow matter intumesces, and then dissolves, 

 leaving a residuum of a yellowish-white colour, which, on being 

 treated with water, gives no indications of the presence of oxa- 

 lic acid. All these properties are common to it with the green 

 substance extracted by the same processes, from the yet green 

 leaves of the same tree, with modifications of colour only. The 

 differences which these two matters present are, the solubility in 



