362 



» KNOWLEDGE ♦ 



[Oct. 27, 1882. 



would appear impoaaible that it could iniKnito from one part to 

 another, and this would bo tho case if no other substance wore 

 pnrAont ; but phosphate of pi>ta9siuni is nbsurbod by the plaitt, niui 

 thia coming in contact with the albunipuoids, renders them soluble; 

 ther cftn now pass thronijh the cell-walls of the stem, and upwards 

 itito the seed, where they are stored up for future uso. Phosphates 

 are also necessary for the production of certain fats, of which they 

 form a p*rt, for the fat of the horse-chestnut and oak contains n smiill 

 percvntage vt phosphorus. Of the other salts sucked up by the 

 n.n.>ts, the sulphate of lime is worthy of mention, as it is necessary 

 to the formation of albumenoids, sulphur beiuR an essential injjre- 

 dient of the»<! matters, whereas phosphorus is not ; and also many 

 essential oils require this element in their composition, and it is to 

 its presence that the oils of black mustarvl and garlic owe their 

 [w'culiar pungency. 



The function which many of the other ingredients found in the 

 ashes of plants perform is still somewhat uncertain, but all experi- 

 menu indicate that potash, lime, and magnesia (the alkaline earths, 

 as these two last are termed) are indispensable to the lifo of the 

 pUnt, and that the absence of irvin is accompanied by abnormalities 

 of growth. When a soil contains no iron, and this dues not 

 eocnr naturally, the foliage loses its green colour, the loss 

 teing due to the non-formation of chlorophyll, or the green 

 colouring matter, and when this is absent, tho |<rocos8 of assi- 

 milation as performed by tho leaves ceases, and thercforo tho 

 plant is in an unhealthy condition ; when wo como to speak of 

 the respiration ard assimilation of plants, in explanation of these 

 terms will bo giron. but at present a few words on the use of potash 

 soda and silica will not bo out of place ; but we will not attempt 

 to dilat« on tho uses of other ash ingredients, such as chlorine, for 

 as before stated, there is no accurate information concerning them, 

 but that they are requisite is certain, whilo what their function may 



For all general purposes, tho chemist considers that the alkalies, 

 potash and soda, are interchangeable ; that what soila will do, so 

 will potash, and as tho former is tho cheapest, it is therefore tho 

 roo«t frequently employed. Plants, however, detect a difleronce, for 

 we find both soda and potash present in their ash in varying quan- 

 tities, and neither of them entirely absent, so that each must have 

 a distinct part to play ; still, to a certain extent they nro inter- 

 changeable, for cultivation greatly alters tho proportions in which 

 they are present, and this alteration is very marked in tho 

 case of the asparagus, which when growing wild, contains equal 

 quantities of these bases, but by cultivation nearly tho whole of tho 

 soda disappears, while the potash increases nearly threefold. Silica 

 or sand is to be found in every soil, cither in tho free or combined 

 slate, and hence we might suppose that it was indispensable, and 

 certainly it exiau in every plant in largo proportions, more espe- 

 cially in tho hard outer parts, the straw and stems containing a 

 very large quantity of this substance, which is generally considered 

 to bo necessary for their rigidity. There are some very remarkable 

 instances known in which deposits of silica aro found in plants. 

 Very notable is that occurring in tho joints of tho bamboo, resemb- 

 ling opal, and bearing the namo tabaiheer ; but yet, though silica 

 exists universally in plants, its absence (under artificial conditions) 

 does not seem to prevent their full development. 



The alkaline earths, as well as potash, seem to bo neeessarj- for 



the formation of tho various salts, such as tho oxalate of lime in tho 



leaves of l<eot and in the common rhubarb, or tho oxalate of potash 



in tho wood sorrel. These bases are introduced in tho form of 



nitrate and phosphate or sulphate, but in the plant they sepiirato 



from tho acid, and combine with new acids, which aro elalwratcd 



through tho agency of tho leaves. Having glanced at tho functions 



|«rformcfl by thn mineral constituents, wo will pass on to those of 



fhc leaves, and hero as before, no attempt will be made to answer 



the question, llow do the leaves act!' but rather our intention is 



t.. show tho results of their action. Tho leaves nro the means 



• : . tho pUnt communicates with tho air, absorbing from 



. riion which is injurious to the life of animals, namely, 



u'id gas, which consists of carbon and oxygen; under tho 



^' :.'; of sun-light these two conifHinents are separated in tho 



!>i»f, the one from tho other, tho carlwn or solid part remaining in 

 r ha plant to form all the various compounds, such as starch oil 

 und acids, while tho oxygen is exhaled into the air for tho uso of 

 Hnimola; this retention of carbon and cenvcrsion into starch, &c., 

 has been termed assimilation to which wo have already referred ; 

 now wo can appreciate tho immense importance of plants of all 

 kmds, for without their aid tho atmosphere would become 

 iu> overburdened with tho harmful carbonic acid, that it 

 could no longer support life nor combustion. A small experi- 

 ment will readily dcmonstmtc the action of leaves on carlxjnic 

 •cid ; if a green laarel-leaf, immersed in a glassful of spring-water, 

 be exposed to sun-light, a number of small bubbles will soon bo 

 noticed on th« iurface of tho leaf. In a short time they will 



increase in size, and finally float to tho surface, when, by proper 

 means, they can be collected and shown to eousist of oxygen, 

 which possesses the pnq>erty of causing a glowing splinter of wooti 

 to buret into flame when introduced into it. This oxygen has been 

 pro<luced by tho decomposition of tho carbonic acid dissolved in 

 tho water. It would be incorrect to sujjposo that tho leaves 

 absorb no oxygen, but always give it out, for at all times a 

 proportion of oxygen is inspiivd, and in tho dark, carbonic acid is 

 exhaled, y»t tho quantity is always less than that of the oxygen ex- 

 haled during the day, and at low tempeiatiiros the amount of oxygon 

 absorbed exceeds that of the carbonic ai-id. Uow to account for 

 tho production of starch from tho materials at the disposal of tho 

 plant is somewhat difticult ; but theoretically, six volumes of car- 

 bonic acid combining with five volumes of water produce starch, six 

 volumes of oxygen being liberated ; but when onco tho starch is 

 produced, wo know, from labonitory oxi)erimouts, that sugar can 

 easily be i)roduced from it, as well as oxalic acid, Ac. Tho purpose 

 of the loaves is not only to collect air food, but also to got rid of 

 superfluous water, for tho root* are continuolly pumping in water 

 laden with mineral fotid, so that to allow of tho circulation and de- 

 position of this food tho water must bo got rid of. This water is 

 exhaled from tho leaves in the form of invisible vapour, but the 

 quantity depends on the statoof the atmosphere, which whon moist 

 almost wholly prevents exhalation ; on tho other hand, in vory dry 

 weather, exhalation takes place too rapidly, and tho plant withers. 

 Light eiorts also a'very great influciioo ; the stronger tho light the 

 greater is tho amount of water exhaled, and, generally speaking, 

 tho maximum occurs shortly after midday. During hot and dry 

 weather a grass plant has been known to exhalo its own weight of 

 water during tho twenty-four hours. From what has been now said, 

 it will bo seen how necessary are plants to animals, and animals to 

 plants, for without the ono the other would not long survive, for 

 when tho atmosphere became exhausted of carbonio acid, which is 

 formed by animals, the i)lunts would then have no means of build- 

 ing up starch, Ice. The great difTerenci- between plants and animals 

 should also be noted, that whereas the plant is continually feeding 

 only to increase and store up material, the animal foods to increase 

 and repair tho waste that is continually procooding. 



A TiiiNriEnsTORM in tmr Mattkeiiobn. — Mr. Alfred S. M. But- 

 tomer writing from l.ivnsanne, says : — " A short account of a 

 summer storm on tho Alatlerhorn may interest somo of your 

 readers. Our party consisted of my wife and myself, with two 

 guides. We had been rather long in making tho ascent, owing to a 

 considerable quantity of snow and ice on the rocks, and it was ono 

 o'clock before wo left tho summit. Tho morning had boon fine and 

 warm, but about noon Fnow fell. On the top tho sun camo out, and 

 tho view on tho Italian side was perfectly clear. About five 

 minutes after commencing tho desiint the sky suddenly bocamo 

 dark, and snow fell in such density that, as ono of our party 

 described it, you could grasp a hamlful from tho atmosphore. 

 A peal of thunder made our guides hurry on. Directly after- 

 wards wo hoard a sharp crack, resembling the report of a 

 rifle, and each of us felt a slight shock in tho head. A peal 

 of thunder followed instantly. The guido who was carrj-ing 

 an ice axe threw it away in alai-m. A second and much louder 

 crack followed in about a minute, and wo all oxporionced a powerful 

 shock. Thn guides felt it in the head, and ono of thom complained 

 of a severe headache for tho rest of tho day. My wife described it 

 as passing through the body. I felt it entirely in tho knoes, which 

 seemed as if momentarily diHlocatod. Thunder followed imme- 

 diately as before. After this, there were a few distant ))oalH of 

 thunder, and in an hour the snow ceased and tho sun eaino out. 

 About a foot of fresh snow had fallen, which mode the doscoiit 

 tedious, and necessitated passing a 8Ccon<l night in tho Zonnatt 

 cabano. Somo friends who liad ascended tho Weisshorii on tho 

 same day had neither snow nor thunder. — Times. 



Sample Box, with all ths kinds. 



>iiioro."-0«../nTn 



Palinlirt if Ptnt ami renholileri. 

 MACKITEN k CAMKRON, 33, I1i.»ir-»tiii^st, Hnmnusnii 



!<IIIt>l:WI TQ UKS MlJMTT's OOVKSKKKST Ol'IMI'l!n. (Kit. V. 



