Notes and Memoranda. 819 



action in the sun on cometary matter, and other facts adduced 

 by the " Wrangler," all point to the conclusion that the laws we are 

 acquainted with do not explain the whole system or cosmos. As 

 the " Wrangler's " paper is only a pamphlet of fifty-six pages, we 

 abstain from extracts, merely recommending it to the notice of 

 those who like to see inquiry stimulated, and the best established 

 beliefs re-examined from time to time. 



NOTES AND MEMORANDA. 



The Colour of "Water. — Father Secchi, in a paper on " Star Spectra," in 

 " Comptes Eendus" (1867, No. 14), says : " Having ascertained that the spectrum 

 of sea-water is destitute of red at small depths, and of yellow and green — at least 

 of their greater part — at successively greater depths, at which the water has a 

 blue or violet colour, I wished to see if the same absorptions were exhibited in 

 glaciers. Profiting by the incident of an artificial grotto having been dug in the 

 glacier of Grindelwald, I made some experiments on this subject. The grotto in 

 question is about 100 metres deep, its walls are transparent, and illuminated by 

 sunshine passing through the ice. This light has a fine blue tint, in which the red 

 is extremely weak, so that in the grotto human faces have a frightfully cadaverous 

 aspect. Looking from a certain depth in this grotto back towards the entrance, 

 the light there appears red, owing to the effect of contrast. A spectroscopic 

 examination shows the light in the grotto to be almost deprived of red, and to 

 have the yellow greatly diminished. The thickness of the ice is not sufficient to 

 produce a more complete absorption. It is said to be about fifteen metres thick, 

 but I should say less. The ice is perfectly compact and continuous in its texture. 

 It is limpid as crystal, and contains here and there groups of air bubbles. Its 

 hardness is not great; an iron point easily penetrates it. The result is thus 

 identical with that which is obtained with sea- water at similar depths ; and as in 

 the Alpine ice we cannot suppose the presence of extraneous colouring matter that 

 might be presumed to exist in the sea, it follows that the true colour of water 

 is a blue mixed with violet, which grows darker as the thickness traversed by 

 the light increases." 



Sulphuric Acid eormed by a Mollusk. — M. M. S. de Lucca and P. 

 Panceri state, in " Comptes Eendus" (1867, No. 14), that the salivary organs of 

 the Dolium galea secrete a fluid which contains more than three per cent, of sul- 

 phuric acid. They examined two specimens caught in the Gulf of Pozzuoles. 

 When filled with liquid, the glands, two in number, are larger than ordinary 

 fowls' eggs, and weigh about seventy grammes. They are formed of two distinct 

 parts — one small and opaque, close to the excretory orifice of the gland ; the other 

 large and transparent, the membrane enveloping it being very thin and white. 

 When incisions are made, so that the lower part of the gland comes in contact 

 with the air, gaseous bubbles of pure carbonic acid are disengaged from the cul de 

 sac tubes, of which almost all the gland is composed. A gland weighing seventy- 

 five grammes discharged under water 200 cubic centimetres of carbonic acid. The 

 liquid contained in the gland tastes like lemon juice, acts on marble, and changes 

 the colour of litmus. A series of experiments show it to contain sulphuric acid. 

 It was previously known that the Dolium galea ejected an acid liquid from its 

 mouth which effervesced with carbonates, and when analysed by M. Baedeker, gave 

 2'7 per cent, of sulphuric acid. The authors of the paper state _that_ they will 

 continue their researches with a view to discover how the sulphuric acid is pro- 

 duced, and what function it performs in the economy of the animal. They say 

 this Dolium " is the first animal which they knew of capable of making sulphuric 

 acid by an unknown process." 



The Colour Question and the Lunar Eclipse, Sept. 13th.— Eeferring 

 to the accounts of this eclipse we published in our last number, we may say that 



