Sept. 22, 18S2,'] 



♦ KNOAVLEDGE 



283 



the engines would he about 20 ft. below the water-line ; all the 

 water sudveU through this valve was discharged from the ship's side 

 at the water level, after having passed through the t-ondcnscr. This 

 condensing water was as brilliant with phosjihorescence as that at 

 the surface, and the mingling of the two was quite invisible. This 

 shows, then, that the water was impregnated with the organisms 

 that cause the light just as thickly at 20 ft. deep as at the surface. 

 And I would ask to what depth does this phosphorescence extend ? 

 or are the organisms that cause it universally distributed over a 

 certain area to an unknown depth, and only flash into existence, as 

 it were, when near the surface ? 



It was a calm night, with a cloudless sky, and for half-an-honr I 

 enjoyed the novelty of this milky sea before turning in again, though 

 I believe we were nearly two hours passing through it altogether. 

 It was curious, also, to note how much darker the sky appeared at 

 the horizon— [doubtless an effect of contrast. — Ed.] — where the line 

 between sea and sky was very definite, than immediately over head. 

 H. P. V.VCIIER. 



'A GLASS OF WINE." 



[569]— In the article by Dr. Lowe, headed " A Glass of Wine," 

 which appeared in Knowledge of Aug. 25, there is a want of pre- 

 cision of statement as to what is to be understood by the terra 

 "alcohol." This uncertainty may lead to undue apprehension in 

 the minds of some readers when the .medical aspect of a glass of 

 wine comes to be noticed, as no doubt will be the case in subse- 

 quent numbers of Dr. Lowe's paper. The matter will perhaps 

 strike you as important enough to call for some explanation or 

 correction. 



When Dr. Lowe states that "port and brown sherry contain, 

 naturally, about 22 per cent, of alcohol by volume," he surely must 

 mean 22 per cent, of proof spirit, the alcohol metric standard of 

 this country ; 22 per cent, of pui-e alcohol by volume corresponds 

 to 38'87 per cent, of proof spirit, as shown by the tables in Thudi- 

 cum's and Dupre's " "rreatise on Wine," and in other accepted books ; 

 22 per cent, of alcohol by weight answers to 40'07 per cent, at proof — 

 a still higher quantity. In point of fact, no natural wine contains 

 so much as 39 per cent, of proof spirit by volume. A wine may be 

 fortified by the addition of strong spirit up to this point, but in the 

 natural state, 20 per ceut. of self-developed proof spirit would be 

 more than the average. 



There are other statements in the last paragraph of the article 

 affected by the same misuse of the term alcohol. It would be, 

 indeed, a terrible reflection to the moderate drinker that, in every 

 pint of port or sherr}^ imbibed by him, he was consuming two-and- 

 a-half wine glasses of pure alcohol ! — two-and-a-half glasses of proof 

 spirit, which is about half the strength, would not alarm him quite 

 so much. W. H. Joitxstox. 



[570]— Dr. Lowe, in his article on "A Glass of Wine," m.-ikcs 

 rather a curious mistake, which you may perhaps think it worth 

 while to correct. He states that methyl, ethyl, and amyl alcohols 

 are isomeric ! Uamologous is probably what he means. H. F. 



POISONOUS LIZARD. 



[571] — A poisonous lizard is well known amopgst the jilanters in 

 the west-end of the island of Jamaica. When living there some 

 years ago I often heard of it, but never saw one. The planters 

 call it the " Galliwasp." No doubt it is the Heloderma horrida of 

 Dr. Wilson. Solancm. 



BOTANICAL REPULSION AND ATTRACTION. 

 [572] — Thank you for your outspoken words on " Elementary 

 Botany Books." The last sentence in the review has been 

 thoroughly verified in my case — viz., " all the good they will ever 

 get from them will be a profound and deeply-rooted hatred of 

 systematic botany. I had to cram so n>ncl> technical botany into 

 my brain from such books as you refer to, and condemn, for my 

 eiamination (by Professor Bentley), that the disgust at tho very 

 name of botany was intense ; when my oyo lighted upon a botanical 

 work, either in my library (fur I did not yield to tho temptation to 

 burn them), or on a bookstall, that day, from that moment, I con- 

 sidered spoilt. This hatred of systematic botany haunted me for 

 nearly twenty years, during which time I never opened a book upon 

 the repulsive subject. Two or three years ago a friend asked mo 

 out to the fields "to communo with wild Uowers " ; with much 

 persuasion I consented, and I found that botany, like all else, 

 had two sides to it, and, unfortunately, that tho seamy side was tho 

 Hr.st one presented to mo in tho text-books, and which had so dis- 

 gusted me. Since, however, my friend showed mo its refined face, 



I have become an enthusiastic botanist, and cannot find food enough 

 to satisfy my botanical appetite. I have devoured Hooker, Ben- 

 tham, Bentley, Bobington, Lindley, and Lubbock, and still my 

 appetite is craving for more. The relishes I offer it these days are 

 Grant Allen's Vignettes and Evolutionist, and the tit-bits that 

 appear from time to time in Knowledge from the pen of tho same 

 interesting writer. Could you, sir, not induce Mr. G. A. to write a 

 book on botany on the lines" pointed out in the review ? 



Beccabcxga. 



TARNISHED DAGUERREOTYPE. 



[573]— The tarnish referred to by "F." is oxide of silver, and it 

 can be removed by floating over the plate a solution of cyanide of 

 potassium. The strength of the cyanide solution will depend on 

 the amount of oxide to be removed. If tho discoloration is very 

 dark, the cyanide must be strong, but a slight oxidation may be 

 removed by a weak solution. A small lump of cyanide may be put 

 into, say, two ounces of water, and in about two or three minutes 

 the solution may be poured over the plate repeatedly. The solution 

 will, of coui-se, at first be weak, and the effect, as the cyanide dis- 

 solves, must be watched. As soon as the tarnish disappears, tho 

 plate may be washed in clean water, and then dried over a spirit- 

 lamp or by a bright fire. The plate may be held by one comer with 

 pliers all through the process. As the cyanide of potassium is a 

 deadly poison, the greatest care must be taken in using it. 



The daguerreotype referred to is " tinted." This colour is only 

 on the sui-face, and will probably be removed by the cyanide and 

 water in washing. The surface of the picture must not be touched, 

 or it will be injured. Dust may be removed with a very soft 

 brush. 



Daguerreotypes, when the air is carefully excluded, are very 

 permanent ; they should be covered with glass, and tho edges 

 bound together with gummed paper. But all daguerreotypes do 

 not require even this protection, as I have in my possession many 

 portraits taken over twenty-five years since by Messrs. Beard ifc 

 Foard, which are as perfect as on the day they were taken, and they 

 have had no other protection than a grooved deal box. 



A. Brothers. 



TURKISH TOBACCO. 



[574] — I see W. P. wishes to know " where Turkish tobacco, 

 mentioned by Constant Header, page 79, Vol. II., can be obtained." 



The only place I ever got it was in the Bazaar at Constanti- 

 nople. It is cheap ; the best, if I remember rightly, being about a 

 mejidieh (3s. lOd.) an oke (or 2 lb.). Whether it "is mild— that is, 

 whether it contains less of the active principle of tobacco than 

 other sorts — I am uncertain. The water throngh which the tobacco 

 is drawn in the nargileh becomes very much discoloured and offen- 

 sive. The tobacco is coarse and uninviting in appearance. 



At Athens they give you quite a diffei-ent sort of tobacco, which 

 1 found hot, pungent, and too strong for my delicate stomach. 



TUNBEKI. 



SINGULAR EFFECTS OF ALCOHOL. 



[575]—" Mephisto's" letter. No. 537, p. 250, I quite agree with, 

 although the quantity he mentions (a teaspoonful of brandy) is 

 very small, and would have scai-ccly any effect on very many 

 people. 



I am very sensitive to alcohol, and one of its effects on mo is 

 I)eculiar, I think. If I drink an ordinary glass of beer or stout, 

 and sit quite still after doing so — say reading for about twenty 

 minutes— and then attempt to speak or move my mouth in any 

 way, tho attempt is accomiianied by exceedingly sharp pains on 

 each side of the face, just below and in front of tho ears. This 

 effect docs not follow if, instead of sitting still, I work actively 

 after drinking. I know no other person similarly affected, but 

 perhaps some of your correspondents do, and will kindly explain. 



I very seldom taste, and never more than one glass, and stout 

 snits mo best, excepting brandy, which I take in two, and occasion- 

 ally three, teaspoonsful. Ueo Fido. 



Letters in Tvi'E.— Size of Rising Moon, V>y G. E. : Locnl 

 Weather Ix)re, by Michael Renrden ; Singular Mental Illusion, by 

 W. H. Perkins; Physiological Experiment, by Z. ; The Use of 

 Drunkenness, by J. Ra'iph ; Talking Canary, Ac, by Charles L. Cane ; 

 New Method of Preserving Organic Bodies, by W. Matiieu 

 Williams ; Defects of Bicvcles, by John Browning and H. T. 

 Round; Jordan-Glycerine B'aTOmeter. by C. J. W. ; Dr. Hunter's 

 Experiments, by Mathildo Van Eys ; Monkey and Mirror, by Deo 

 Fido. 



