salt mixed with water in a flower pot, will expedite the 

 opening of a rose-bud, or other flower, when plucked from 

 the parent branch. 



Here I will observe, that if a small bit of nitre be added 

 to the pure water, in a vase containing flowers ; the water 

 changed every day, and a small piece of the flower-stalk 

 cut off each time of the change of water, the freshness of 

 the flowers may be preserved for a considerable length of 

 time. 



Secretions. The sap, when exposed to the action of the 

 air, light, and heat, by the leaves, becomes a new fluid, 

 which assumes the peculiar flavour and qualities of the 

 plant. Gum is one secretion, which oozes from the cherry, 

 and other trees ; resin, and turpentine, are of the same 

 nature ; as is, also, the milky juice of the fig, poppy, &c. 

 Almost all the fruit trees yield some sort of gum. And a 

 species of the Acacia tree, in Arabia, yields the Gum 

 Arabic, which is the chief nourishment of the nations of 

 those parts, who obtain it in great quantities from inci- 

 sions which they make in the trees. This Gum Arabic 

 is now in frequent use in our own country ; and forms a 

 good aliment for young children ; particularly when on a 

 sea voyage, where milk cannot be commanded. 



Another secretion is Caoutchouc, or Indian rubber, which 

 is obtained from several species of trees in South America 

 and the East Indies. The botanic names of the two 

 species found in Cayenne, S. A. are Hacvea caoutchouc and 

 Jatropha elastica. The fluid is collected from the tree 

 by incision ; the colour is, at first, a yellowish white, but, 

 by exposure to the air, it becomes dark. Moulds made of 

 clay, in the form of bottles, shoes, &,c. are dipped into it 

 repeatedly, and afterwards dried, and, when of a sufficient 

 thickness, the clay moulds are easily crushed, and the 

 pieces emptied out. 



The natives make vessels of it for containing water and 

 other liquids; and, while soft, all sorts of designs are traced 

 upon it. On account of its inflammability, it is used, at 

 Cayenne, for torches. When warmed, it gives out a pecu- 

 liar odour, but not an unpleasant one ; from its smoke, a 

 considerable quantity of very fine lamp black may be col- 

 lected. 



Rectified oil of turpentine, at common temperature, 

 will afford a complete solution of it ; and, when mixed 

 with a solution of wax, in boiled linseed oil, it composes 

 an elastic varnish, with which they cover balloons ; and 



which might be applied to a variety of useful purposes. 



The fresh cut surface of the Caoutchouc will unite to- 

 gether by simple contact, and, by a proper pressure, may 

 be brought so completely in union, as to be no more liable 

 to separate in that part, than any other. 



The Caoutchouc, when cut in slips and softened by im- 

 mersion in boiling water, may be drawn out to seven or 

 eight times its original length, and will afterwards, by its 

 elasticity, resume very nearly its former dimensions. Dur- 

 ing its extension, a very sensible warmth is produced, as 

 may be discovered by applying it between the lips. 



Another secretion to be found in every vegetable, in a 

 greater or less degree, is sugar ; but generally mixed with 

 gum, sap, or other ingredients. It abounds most in fruits, 

 and roots as the beet, carrot, &c. : but, more particularly 

 in the Saccharum, or sugar-cane. 



The odour of plants, is a volatile oil of a resinous na- 

 ture, communicated to the surrounding atmosphere. This 

 volatile oil is sometimes distributed through the whole 

 plant, as in the Bohemia Angelica ; sometimes it exists 

 in the bark, as in Cinnamon. Balm and Mint contain 

 their oils in the stem and leaves; Elicampane, and the 

 Iris of Florence, in the root ; Rosemary and Thyme, in 

 their leaves and buds ; Lavender, and the Rose, in the 

 calyx of their flowers ; Chamomile, Lemon, and Orange 

 Trees, in the petals. Many fruits contain it through their 

 whole substance, such as Peppers, Juniper, &c. ; Oranges 

 and Lemons, in the zest or peeling which encloses them, 

 &c. 



Fecula is the general name given to the farinaceous 

 substance contained in all seeds, and in some roots as 

 Wheat, Indian corn, the Potato, Parsnip, &c. : it is in- 

 tended by Nature for the first aliment of the young plant. 



Colour. The fixed colours of opaque bodies are, in all 

 probability, owing to their absorbing some of the coloured 

 parts of white light, or rays of the sun, and reflecting 

 others ; their immense variety arising from a mixture of 

 the reflected primitive colours, in various number and 

 proportion. It is impossible to say upon what cause the 

 disposition of reflecting certain colours, in preference to 

 others, may depend. The probability is, that it arises 

 from the different textures of the surfaces. 



There are some flowers, the petals of which are, in dif- 

 erent parts of the same leaf, of different colours ; as of the 

 Heart's Ease, for instance, which, if examined with a good 



