September, 1913. 



KNOWLEDGE 



353 



Wash the prints in several changes of water and then tone in 

 the following bath — 



Borax ... ... ... 35 grains. 



Sodium Acetate ... ... 35 grains. 



Water (Distilled) ... ... 7 ounces. 



Gold Chloride ... ... ... 1 grain. 



This solution should be made up as required, as it will not 

 keep. The prints are toned in this to a chocolate brown. 

 They are then rinsed and placed in the following bath — 



Potassium Chloroplatinite 



Water 



Phosphorous Acid, 1-12 



5 grains. 

 10 ounces. 

 75 grains. 



This solution may be used over and over again until 

 exhausted. If the preliminary toning with gold is not carried 

 too far the final treatment in the platinum bath should yield a 

 good black. The prints after toning are well washed and 

 then fixed in a solution of hypo of the following strength — 



Hypo ... ... ... 3 ounces. 



Water ... ... ... 20 ounces. 



This should be freshly prepared and about twenty grains of 

 soda carbonate added to it when fixing platinum-toned 

 prints, or, if preferred, the prints after toning may be rinsed, 

 and then placed in a five per cent, solution of soda carbonate 

 until ready for fixing. After remaining in the fixing bath for 

 about fifteen minutes the prints should be washed in running 

 water for two hours. When it is desired to tone with 

 platinum only without the use of the preliminary gold bath, 

 the following formula for the solution may be employed — 



Potassium Chloroplatinite 



Water 



Hydrochloric Acid 



i grain. 

 30 ounces. 

 J drachm. 



or in place of the above we may use one containing chrome 

 alum, thus — 



Chrome Alum ... 

 Potassium Chloroplatinite 

 Water 



120 grains. 

 1 grain. 

 10 ounces. 



When the prints are toned they are placed, after a slight 

 washing, in a five per cent, solution of soda carbonate and 

 allowed to remain there until all are ready for fixing. 



SULFINOL DEVELOPER.— A further addition to the 

 already large number of bodies which act as developing 

 agents has recently been made by the preparation of a 

 substance— by M. J. Desalme — termed " Sulfinol." Those 

 who wish to experiment with this new compound will now 

 be able to do so, as it is being manufactured by the Societe 

 des Matieres Colorante et Produits Chimiques de Saint Denis, 

 105, Lafayette, Paris. 



Sulfinol is a bluish-grey powder only slightly soluble in 

 water, but much more soluble in water containing soda 

 carbonate and other alkalies. It appears to contain the 

 sulphonic group — SO»H, and somewhat resembles Glycin in 

 its slowness of action. It gives soft negatives having 

 excellent gradation and good detail in the high lights. The 

 colour of the deposit verges on brown. The addition of 

 bromide has the effect of greatly slowing the developing 

 action. Sulfinol appears to be specially useful in the 

 development of bromide prints and enlargements on account 

 of the warm tones obtainable by its means. The developing 

 action, however, is very slow, the image taking about three 

 minutes to appear and requiring from seven to eight minutes 

 for complete development ; but the length of time required 

 does not appear to cause any fogging action to take place over 

 the lights. We append the following formula recently 

 published by Captain K. Hergeth in " Wiener's Mitterlungen " 

 for the preparation of a sulfinol developer for bromide paper — 



Sulfinol ... 



Soda Sulphite (Crystals) 

 Soda Carbonate (Anhydrous) 

 Water ... 



10 to 15 grams. 

 40 to 50 grams. 

 30 grams. 

 1,000 c.c. 



The soda sulphite and carbonate are first dissolved in 

 about 200 c.c. of water and then the sulfinol added, the 

 solution being finally made up to 1,000 c.c. with the addition 

 of water. This developer keeps well and is always ready for 

 use. Sulfinol may also be employed in conjunction with 

 hydroquinone when a developer is obtained which acts much 

 more rapidly and can be used for both plates and papers. 

 Prints made upon bromide paper may be developed with the 

 mixed solutions in about two minutes, — without bromide — ■ 

 and the image will have a pleasant warm brown colour. Some 

 six or eight prints may be developed in the same solution, 

 although after the first two or three it becomes much slower 

 in its action. Finally, the sulfinol-hydroquinone developer 

 may be said to supply the means for obtaining prints of a 

 warm tone by direct development, and in this way is a useful 

 alternative to that of after-toning. 



ZOOLOGY. 



By Professor J. Arthur Thomson, M.A., LL.D. 



ACCESSORY CARTILAGE IN BAT'S WING.— Oskar 

 Torne recalls attention to an interesting extra cartilage which 

 lies to the outer side of the last joint of the little finger in all 

 Vespertilionidae. It is not bound to any other part of the 

 skeleton, and has considerable independent mobility. Fibrous 

 strands of connective tissue extend from the accessory 

 cartilage into the posterior margin of the wing, and probably 

 move it in some independent way during flight. What the 

 accessory cartilage really is remains obscure, and must remain 

 so until its development in the embryo is worked out. 



EXTRAORDINARY MODE OF PARENTAL CARE 

 IN A FISH. — In one of the rivers of New Guinea the explorer 

 Lorentz found a remarkable fish, Kurtus gulliveri, whose 

 parental care has been described by Professor Max Weber. 

 In the mature male a bony process on the back of the skull 

 grows forwards and downwards, and forms a ring or " eye." 

 In this, somehow or other, a wreath of eggs is attached. Each 

 egg bears radiating filaments — over a hundred in number — 

 which unite into strings, and these form a cylindrical band. 

 This band passes through the bony ring, and the male carries 

 the eggs on the top of his head. The details of the curious 

 attaching filaments which fasten the eggs together have recently 

 been studied by Professor F. Guitel, who compares the 

 filaments with those of another fish, Clinus argentatus. The 

 adaptation is very remarkable, and one would like to know 

 more in regard to the manner in which the eggs come to be 

 fastened to the bony ring. 



THE HERMIT CRAB AND ITS BORROWED 

 SHELL. — In his recently published memoir on the Hermit 

 Crab — an admirable piece of work — Mr. H. Gordon Jackson 

 discusses the old question whether the crustacean forcibly 

 ejects the mollusc. Bell argued from the frequent freshness 

 of the shells that the hermit must eat the mollusc out of its 

 home, and fishermen sometimes catch the soldier hermit crab 

 (Eupagurus bcmhardus) devouring a whelk. But Mr. 

 Gordon Jackson points out that while the argument and the 

 observation are both sound they do not prove that the 

 hermit crab attacks the living Gastropod. " In the first place 

 it is not very conceivable that a hermit crab would have 

 the strength to remove bodily, or the appetite to devour, an 

 extremely tough animal like the whelk." In the second place 

 it is well known that " the cod feeds very largely on the whelk, 

 and that nothing but the operculum is ever found in the fish's 

 stomach. The mollusc's fleshy portion (chiefly the foot and 

 head) must therefore be bitten off while expanded — a com- 

 paratively simple matter to the active and powerful Teleost — 

 leaving the softer (visceral) parts inside the shell." The 

 hermit crab may then clean up the remains and ensconce 

 itself in the emptied shell. 



CHEMISTRY OF THE SILKWORM.— R. Inouye finds 

 that the chemical composition of the silkworm is greatly 



