310 



NOTES AND QUERIES. 



[Oct. 20. 1855. 



An excess of light also has its evils, for it de- 

 velopes an excessive growth of vegetation, the 

 algse throwing off their spores so abundantly, that 

 the whole bulk of the water speedily becomes of 

 a deep greenish brown colour; not interfering 

 with the health of the animals it is true, but ob- 

 jectionable from the fact that everything is 

 effectually hidden from view. This evil also I 

 have successfully combated by drawing off the 

 water and placing it in vessels in a dark closet, 

 thus destroying the vegetable principle, and re- 

 storing it to its former clearness, when it may be 

 used again. To recapitulate ; if care be taken to 

 secure a healthy vegetable growth before the in- 

 troduction of animal life, if the latter be put in 

 gradually, and if the stock be kept at a minimum 

 rather than at a maximum amount, non-success 

 can scarcely follow. For more minute details, 

 reference should be made to a little- half-crown 

 volume issued this week, and entitled A Handbook 

 for the Marine Aquarium^ containing practical In- 

 structions for constructing, stocking, and maintain- 

 ing a Tank, by that eminent naturalist, Mr. P. H. 

 Gosse. W. Alfoed Llotd. 



164. St. John Street Road. 



DE WITT MEDALS. 



(Vol. xii., p. 244.) 



As a descendant, through the female line, of the 

 De Witt family, I should be very glad of some ac- 

 curate information respecting the medal of which 

 G. L. 0. speaks. I have in my possession (an heir 

 loom in my family), a composition cast, apparently 

 from the medal described by G. L. O., less than 

 two inches and a half in diameter. The reverse is 

 as he describes it, very finely executed. The 

 legend has "formidati" (not " formidate). On a 

 scroll above the device are the words — 



" Mens agitat molem, et magno se corpora miscet." 

 Below the device is inscribed — 



"nobILe par FratrVM s^Vo fVror ork 

 trVCIDat. XX AvGVSTi." 



It is obvious that the date is contained in the 

 large letters of the portion which ends with truci- 

 dat, as the year of their murder was 1672. The 

 designer's name is in the corner, " Avby F." On 

 the obverse are the effigies in profile, and facing 

 one another, of the two brothers, with the legend, 

 "Cornelivs De Witt. Nat. A. 1623* Johannes 

 De Witt. Nat. A. 1625." And behind John De 

 Witt, in smaller letters, " Integer vitse ; " and 

 behind Cornelius, " Scelerisque purus." On a 

 scroll beneath the figures, " Hie armis maximus, 

 ille toga." A shield is beneath all, charged with 

 three greyhounds courant. I have besides, a silver 

 medal (also an heir loom), not quite two inches in 

 No. 312.] 



diameter, having on the obverse the effigies of the 

 two brothers in profile, not facing one another, 

 but disposed as in the coins of William and Mary. 

 (I am very defective in numismatic terminology.) 

 The legend is " Illustrissimi fratres Johan. et 

 Cornel. De Wit." The reverse has an orna- 

 mented border, with this inscription : 



" Twee Witten eensgezint, 

 Gevloeckt gehaet gemint, 

 Ten Spiegel van de Grootea 

 Verheven en verstooten, 

 In alles Lotgemeen, 

 Staen naer hundootbijeen 

 Gelijck zij hier nae't leven 

 Zookonstig zijngedveven." 



Round the rim is engraved, "Violenta morte 

 deleti. Hagse Comiti. 20. Aug. A. 1672." The 

 engraver's name is not given. John Jebb. 



Peterstow. 3, 



PHOTOGRAPHIC CORRESPONDENCE. 



Alhumenized Collodion — M. Taupenot's Process. — M. 

 Taupenot commences by describing a process for albu- 

 menizing, instead of varnishing, collodion plates, as he 

 considers albumen a much better material than varnish 

 for that purpose; both on account of its greater trans- 

 parency, and from its being a better protection to the 

 negative. The process is as follows: — The albumen is 

 mixed with 10 per cent, of honey and a small quantity of 

 yeast, fermented and filtered, and 1^ per cent, of iodide 

 of potassium added ; it is poured on the plate in the same 

 manner as varnish, and the plate is then rested against a 

 wall, with its face towards it, to drain until it is dry; it is 

 then passed through a bath of ordinary aceto-nitrate of 

 silver, washed, and immediately afterward through a 

 bath of hyposulphite of soda; and the operation is ter- 

 minated b}' washing the plates. The whole process, 

 with the exception of the short time the albumen 

 takes to dr}', does not exceed one minute ; and is, M. 

 Taupenot says, a perfect protection to the collodion. 

 The employment of albumen in this manner led M. Tau- 

 penot to another process : — that of photography on dry 

 albumenized collodion, which he considers to succeed as 

 well as that freshly prepared and wet. He describes his 

 process in the following manner: — 



On a collodion plate, passed through a silver bath, and 

 washed with distilled water, pour, as in varnishing a 

 tinished plate, the iodized albumen above described, new 

 or old, and let it drain till it is dry. In this state, the 

 plate will keep several daj's. When it is wanted to be 

 used, pass it through the bath of aceto-nitrate (10 parts 

 of nitrate, and 10 of acetic acid to 100 of distilled water). 

 The plate should be left from 10 to 20 seconds in this 

 bath, which ought to have been filtered with care just 

 before using, particularly if it is intended to employ pj'ro- 

 gallic acid to develope the image. The plate should be 

 washed with distilled water, and it can be used either at 

 once, while it is still wet, or it may be kept till the next 

 day, when it will be found to be as sensitive as collodion 

 used in the ordinary manner. 



It is not necessary to develope the image as soon as it is 

 taken, that can be done the next day. A solution of 

 gallic acid, with the addition of some drops of fresh aceto- 

 nitrate of silver, developes the image perfectly, but slowly, 

 from a quarter of an hour to three days even, according 

 to the time of exposure being required and the quantity of 



