1855.] 



OBSERVATIOxVS ON THE COLOUKLNG MATrERS OF FLOWERS. 



1U3 



flowei's the propei'ty of becoming yellow ■when in contact with alkalies 

 may be tuteoline. 



If the petals of white roses be boiled with distilled water, and a 

 little carbonate of soda and sulphate of copper be added to the decoc- 

 tion, as is done with the decoction of woad, a liquid is obtained pos- 

 sessing a bright golden-yellow colour which may be employed in 

 dyeing yellow. This liquid will give a, fine yellow tint to linen and 

 cotton fabrics, and nearly all white flowers will furnish similar results. 

 I have dyed pieces of linen and cotton with decoctions of white roses, 

 of the flowers of Spircea filij>endula, Pldladelphus coronaria and Galium 

 Mollugo. 



The matter to which white flowers are indebted for this property of 

 acquiring a yellow colour under the influence of alkalies, dissolves 

 readily in water, still more so in alcohol, but less in ajther. When 

 the superficial layer of the petals of flowers which have been 

 coloured yellow by ammonia is removed, all the cells are seen to be 

 filled with a j'ellow fluid, in which no granules are to be perceived. 



Dark Red Flowers. — With boiling water or alcohol, the flowers of 

 the wild poppy furnish a violet-red solution. This acquires a fine scar- 

 let colour by the action of acids, even when very weak. If ammonia 

 be poured into the liquid thus acidulated, it becomes of a fine violet 

 colour, without the least mi.xture of green. But if, instead of adding 

 ammonia to the acidulated liquid, it is added directly to the infusion, 

 this acquires a dirty greenish-red tint. When the flowers themselves 

 are exposed to the action of ammonia, they acquire a fine violet color, 

 like that obtained with the acidulated fluid. The colouring matter of 

 the poppy therefore differs greatly from the cyanine of jM.M. Fremy 

 and Cloez, for alkalies do not give it a green colour. 



The flowers of Pelargonium zonule also become of a fine violet colour 

 under the influence of ammonia ; theii- colouring matter behaves like 

 that of the poppy. The dark red garden verbena gives a violet-red 

 tint to alcohol. The alcoholic solution, treated with ammonia, ac- 

 quires a vinous colour with a slight greenish tint. If the alcoholic 

 infusion of these flowers be digested with a little dry powdered hydrate 

 of alumina, the latter acquires a light yellow colour, and the superna- 

 tant fluid becomes of a fine red colour under the influence of acids, and 

 of a blue without the least mixture of green by the action of bases. 

 The verbena consequently contains two distinct matters, of which one 

 becomes blue under the influence of bases, whilst the other becomes 

 yellow; it is to the mixture of these two matters that the green colour 

 of the alcoholic tincture of these flowers is due. 



The petals o( Anemone horlensis act like those of the verbena. The 

 flowers of the red pseony become of a pure blue colour under the influ- 

 ence of ammonia. These flowers are rapidly deprived of colour by 

 alcohol ; the tincture which they furnish is but slightly coloured, but 

 it becomes of a deep and bright red by the addition of the smallest 

 trace of acid. The acidulated liquid becomes blue with ammonia, whilst 

 the non-acidulated alcoholic solution acquires a greenish tint. The 

 petals of dark red roses become blue when exposed to ammoniacal 

 vapours, but the colour soon passes to a greenish-blue. Alcohol 

 readily dissolves the colouring matter of roses, but acquires very little 

 colour. The slightest addition of acid communicates a deep red color 

 to the alcoholic solution ; ammonia poured into the acidulated liquid 

 changes it to a greenish blue. 



Rose-coloured Flo-vvers. — These flowers contain a mixture of two 

 juices, of which one is colourless in acid liquids, whilst the other is 

 red. The former becomes yellow when mixed with alkalies, tho 

 second becomes blue, and the mixture of these latter colours produces 

 a green tint. Hence tlie tints which will be acquired by red or rose- 

 coloured flowers, when exposed to the action of ammoniacal vapom-s, 

 may bo easily indicated beforehand. It is clear that the green 

 colour will approach yellow more and more in proportion to the pale- 

 ness of the rose, and that it will have a blue tendency in proportion as 

 tho colour becomes deeper. 



BurE Flowers. — The preceding statements regarding red and rose- 

 coloured flowers applies al.so to blue flowers. The green colour jiro- 

 duce 1 in blue flowers by the action of watery ammonia tends more 

 and more to yellow in proportion to the paleness of the flower. 



Effects of the Mixtlt-e of the white .vsd colored jiices or 

 Flowers. — When flowers of iris, of violets, pieonies, of Cercis siliquas- 

 Irum. (ic, are infused in alcohol, one is struck witli the weakness of 

 t'ut of the alcoholic solution, even when tiic petals arc completely 

 deprived of colour. It appears natural, at first sight, to attribute thi.s 

 decoloration to the influence of the alcohol, which may act as a reducing 

 3 



agent; but a close examination of the facts does not permit us to rest 

 satisfied with this explanation ; and without denying that alcohol may 

 exercise the influence attributed to it by M. M. Fremy and Cloez, I 

 think that tho following theorj-, either alone or combined with 

 that just referred to, may readily account for the circumstances in 

 question. In fact, if, instead of treating the above-mentioned flowers 

 with alcohol, they are infused in boiling water, the watery solution is 

 not more deeply coloured than the alcoholic tincture. It would be 

 necessary therefore to admit that water itself is a reducing agent, 

 which is by no means probable. 



If into these solutions, whether watery or alcoholic, the smallest 

 quantity of a soluble acid be poured, they instantly acquire a bright 

 red colour, far deeper in tint than the original liquid. The kind of 

 acid is quite immaterial, for even sulphurous acid immediately 

 brightens the shade, and reproduces the colour which was only con- 

 cealed. The prolonged action of this acid however soon destroys the 

 colour. Cau it be imagined that the colouring matter would reappear 

 immediately upon the addition of ang acid, if it had been reduced ? 

 and especially on this hypothesis, can we account for the action of 

 sulphurous acid ? I think not. 



In my opinion, the decoloration is due to the mixture of the juice 

 contained in the colourless cells with that of the coloured cells. When 

 alcohol or boiling water acts upon a flower, its organization is 

 destroyed, the juices contained in its cells become mixed, and the 

 colouring matter disappears. The following experiment lends support 

 to this explanation. 



If two equal volumes of a slightly acidulated infusion, either watery 

 or alcoholic, of pooony flowers be diluted, the one with four times its 

 volume of water, the other with four times its volume of an infusion of 

 white flowers, it will be seen that the latter will retain much less color 

 than the former. 



Tho white juices consequently destroy, or rather dissemble the 

 colouring matter. The question now arises whether these juices act 

 as reducing bodies, or whether they simply form colorless combina- 

 tions. The experiments to which I have refeiTed above may, I think, 

 serve to answer this question ; for if reduction tjikesplace, sulphurous 

 acid would not reproduce the coloui-. I consider therefore that the 

 colouring matter does not experience any reduction, and that it forms 

 with the elements of the colourless juices or a colourless combination. 

 In infusions prepared by the action of alcohol or water upon flowers, 

 one portion of the colouring matter remains free, whilst the other 

 enters into the combination just mentioned. It is easy to separate the 

 coloured portion from the colourless, by triturating the liquid with a 

 little artificial phosphate of lime or dry hydrate of alumina ; the 

 coloured part is the first to fix upon the solid body, whilst that of 

 which the colour is dissembled remains for the most part dissolved. If 

 the liquid be filtered, it passes without colour. It may then be colored 

 red by acid, and green or blue by an alkaline solution. — Comptea 

 Rcndus, July 24, 1854, p. 104. 



On tUo Discovery of Microscopic SlicXls lu tlie Lo'H'cr Silurian 

 Kocks*'^ 



BY PROF. ElIBENBEKG. 



{Communicated by Mr. Leonard Homer.) 

 The minute grains of greensand, which are characteristic of many 

 rocks, have a different nature from tlie green earth often met witli in 

 concretionary masses. The former, from the ijluuconie of the Paris 

 calcaire grassier to tho azoic green sand, near Petcrsburgh, appears to 

 consist of green opalescent casts of Polythalamia. composed of a liydro- 

 silicite of iron. The cretaceous greensands of England contain unmis- 

 takeably, these stony casts. In the calcaire grassier and nummulite 

 limestones occur beautifully preserved and perfect examples of 

 Quinqueloculina, llotalia, Textularia, Grammostoma and ,\lveolina. 

 In the Lower Silurian greensand casts of detached cells of Textularia 

 and Nodosaria were found. Prof Forbes said, that Mr. Sorhy had 

 discovered Foraminifcra in the Aynicstry limestone : but as some of 

 the beds with green grains were of freshwater origin, it was almost 

 impossible that all greensand should be derived from this source. 

 Prof. Sedgwick pointed out instances in which the green colour was 

 duo to particles of chlorite. — Sir K. I. Murchison stated, that tho 

 whole group of Lower Silurian strata existed near Petcrsburgh, though 

 only 1,0U0 feet thick : the upper part, representing the Cala limestone, 



* British Association. 



