July 6, 1883.] 



♦ KNOWLEDGE ♦ 



the substance, which can, generally speaking, be obtained 

 gratis from a gas company's works. It is one of the waste 

 products in gas manufacture, and has no other marketable 

 value. Anent the zinc, our remarks in the preceding 

 article are applicable, but a little word may be added here. 

 If the amateur has a small pocket, and is unable to get 

 ^-inch zinc bent, he may use g-inch, and by raising it to a 

 fairly high temperature, he will find it capable of being 

 easily bent. The retail price foi- a cylinder weighing a 

 little over a pound is Is. 9d., or about three times the price 

 of the metal. 



Amateurs often complain that the zincs get dirty, and 

 covered with a white salt when put away after using them. 

 They will experience no such trouble if they will remove 

 the zinc from the solution when the battery is done with, 

 and, after carefully and thoroughly rinsing it with water, 

 wipe it dry with a piece of common calico, and then place 

 it in a cupboard or other receptacle apart from the porous 

 pot (which may be advantageously left in the acidulated 

 water) and the carbon block. 



The resistance of a Bunsen cell is practically nil, being 

 less than the tenth of an ohm. The electro-motive force 

 is, on the other hand, high, being 1-9 or 2-0 volts. 



The cell is useful for laboratory or other experimental 

 work, on account of the intense current yielded by it ; 

 but, on account of its rapid polarisation, it is useless 

 where constancy is required. 



The Grove cell is similar to the Bunsen, the difference 

 being that the former contains a platinum foil in the place 

 of carbon. Its efficiency is about the same as the Bunsen, 

 but it is cleaner, and, being generally made in the flat 

 form, takes up less room. Its cost is about 50 per cent. 

 more than that of the Bunsen. 



SAVAGE AND ANTHROPOLOGIST. 



WHEN the " Special Extra Meeting of the Anthropo- 

 logical Institute " was held at the Piccadilly Hall 

 last week, the Botocudos must have been intensely amused. 

 It must not be imagined that the interviewing in this 

 matter is all on the side of the European. Mr. H. M. 

 Stanley has recorded how, in his South African wanderings, 

 he was persistently humiliated by the consciousness that 

 while he thought he was discovering the savages, the 

 savages would insist upon discovering him. When he visited 

 one of their encampments, they surrounded him as an 

 unusually tame specimen of a peculiar pale-coloured 

 variety of human being. They took off liis clothes to 

 look at his skin, and noted with satisfaction that he 

 would eat the ordinary viands of life. Thus it fre- 

 quently happened that Stanley departed from one of 

 their " towns " with the sorrowful knowledge that the 

 antliropologically-nunded Africans had picked up more 

 infuriiuition about him than he had about them. The same 

 fate befell the Man among the Monkeys. They regarded 

 him as a large and hitherto unknown species of monkey, 

 which " resembled an onion " in so far that it had seveial 

 skins which peeled off easily. In both these cases, how- 

 ever, the European was one among many, whereas at the 

 Piccadilly Hall the odds are all the other way. Neverthe- 

 less, the four Botocudos there evidently consider themselves 

 numerous enough to form a scientific quorum for the dis- 

 cussion between theni.sclves of any more than usually 

 peculiar anthropological curiosity in a tall hat that may 

 chance to enter the hall, with the idea that he is the sight- 

 seer and the Botocudo the sight — and not a very inspirit- 

 ing one at that. But when the special extra meeting 

 of tlie Antliropological Institute appeared on the scene, 



the Botocudos must have been really thankful for the 

 treat provided them. When some Fijian .savages, under 

 the guidance of a missionary, for the first time visited an 

 English man-of-war, they could hardly express their grati- 

 tude sufficiently. " We beheld the men in great numbers, 

 and very industrious at their work," they said, and " we 

 respected them greatly. We beheld the chiefs of the 

 ship, and reverenced them greatly. We young men of this 

 generation were born in blessed times to see such a ship 

 as this. Our fathers saw no such sight." So doubtless 

 the anthropologists and the Botocudos last week equally 

 congratulated themselves upon their good luck. Never before 

 had the anthropologists seen four Botocudos together, one 

 of tliem with a large piece of wood stuck in hei* lip ; and 

 never before had four Botocudos seen so uniformly vener- 

 able an assortment of white men, the majority with oval 

 pieces of glass fixed by wires in front of their eyes, and 

 some of them quite bald. Their fathers saw no such 

 sight. 



Nor is it quite certain that in a cursory comparison the 

 Botocudos would not be able to credit themselves with the 

 superiority. It is true that the old lady of their party has 

 distended her lower lip to the size of a tobacco-pouch, but 

 she has not pinched in her waist to a 6 J, -inch diameter, nor 

 does her husband wear a shiny black funnel, with a brim 

 to it, upon his head. The daughter, too, has obviously no 

 need of stays : and the son's splay feet have been allowed 

 to tread in Nature's free and easy lines ; so that between 

 the swarthy youth inside Piccadilly Hall and the gOded 

 youths upon Piccadilly pavement outside, if an active 

 cockroach were the umpire, there can be little doubt 

 which would be pronounced the most eflective "masher." 

 The manners and customs of the white men, too, are 

 worth noticing. When two of them meet a third, one 

 of the two steps forward, says a few words to each of the 

 others, and then they take off their tall hats and wave 

 them gently towards each other's feet ; and then they put 

 them on again. After that they catch hold of each other's 

 hands and shake them strongly, grinning all the time as if 

 they were happy. Among the transactions of the Anthro- 

 pological Institute of Botocudoland it will, no doubt, be 

 recorded that the English are in many ways — according to 

 the report of the Botocudo deputation that explored 

 London in 1883 — a peculiar race of men, and that the 

 variety known as " anthropologists " are especially remark- 

 able for their age, their fondness for palavers, and their 

 inquisitiveness. — Globe. 



Some kinds of white glass become, in the process of 

 time, more or less deeply coloured under the influence of 

 luminous rays. The most common tints are violet and 

 green. The materials of ordinary glass are somewhat 

 ferruginous and capable of tinging glass with a deep green 

 shade by the protoxide of iron. In order to remove the 

 colouring, peroxide of manganese is added, which changes 

 the protoxide into a sesqui-oxide, which gives a feeble 

 reddish-yellow tint. It is almost impossible to observe the 

 proper proportions of manganese and iron. If there is too 

 much oxide of manganese the glass has at first a violet 

 shade ; if there is too much protoxide of iron the glass 

 will be greenish ; if all the manganese is reduced to a 

 state of protoxide the glass is colourless. The influence 

 of light and air may gradually bring about a partial 

 oxidation of the protoxide of manganese and a violet 

 colouring which increases with time. The Cfironiqiie 

 Ini/ufirielle says a shade which is due to an excess of 

 manganese is observed in the Pinacothek, at INIunich, where 

 the upper windows of the picture-gallery give a verj 

 marked violet light which produces a bad effect. 



