NATURAL PHILOSOPHY. 89 



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made use of this test in a most ingenious manner, to distinguish be- 

 tween the two different methods of dyeing cloth with madder and with 

 garancine. It is difficult and often impossible for calico-printers and 

 merchants to distinguish between the two ; and as the garancine dye is 

 more fugitive than the first, and also of less intrinsic worth, it is some- 

 times substituted for it. There is however, a slight difference in the 

 process of manufacture, madder-dyed goods are, in one stage of the 

 process, passed through a solution of soap to fix the color, whilst in 

 garancine-dyed goods the soap is replaced by hypochlorite of lime. By 

 proceeding as follows, it is easy to distinguish between the two kinds 

 of dye : Let camphor rotate on water in any glass vessel, as previously 

 described, then immerse a small strip of the cloth to be tested. If the 

 rotation stops, we infer the presence of soap, and conclude it to have 

 been dyed with madder. But if, on plunging in the small piece of 

 cloth, the rotation is not stopped, we then arrive at the conclusion that 

 garancine was the dyeing material used. In like manner the purity 

 of water may also, to a certain extent, be tested by dropping a frag- 

 ment of camphor upon its surface. 



CURIOUS ELECTRICAL PHENOMENA. 



Prof. Tyndall publishes the following account of some curious 

 electrical phenomena observed by Mr. R. Watson, and a party of 

 tourists in ascending a portion of the Jung frau Mountain in Switzer- 

 land. Mr. W., in a letter to Prof. Tyndall says, On the 10th of July, 

 1863, I visited with a party of three, and two guides, the Col de la 

 Jung frau. The early morning was bright, and gave promise of a fine 

 day, but, as we approached the Col, clouds settled down upon it, and, 

 on reaching it, we encountered so severe a storm of wind, snow, and 

 hail, that we were unable to stay more than a few minutes. As we 

 descended, the snow continued to fall so densely that we lost our way, 

 and, for some time, we were wandering up the Lotsch Sattel. "We had 

 hardly discovered our mistake when a loud peal of thunder was heard, 

 and shortly after, I observed that a strange singing sound, like that of a 

 kettle, was issuing from my alpenstock. We halted, and, finding that 

 all the axes and stocks emitted the same sound, stuck them into the 

 snow. The guide from the hotel now pulled off his cap, shouting that 

 his head burned; and his hair was seen to have a similar appearance to 

 that which it would have presented had he been on an insulated stool, 

 under a powerful electrical machine. We all of us experienced the 

 sensation of pricking or burning in some part of the body, more 

 especially in the head and face, my hair also standing on end in an 

 uncomfortable but very amusing manner. The snow gave out a hiss- 

 ing, as though a heavy shower of hail were falling ; the veil on the 

 wide-awake of one of the party stood upright in the air, and on wav- 

 ing our hands, the singing sound issued loudly from the fingers. When- 

 ever a peal of thunder was heard, the phenomena ceased, to be re- 

 sumed before the echoes had died away. At these times, we felt 

 shocks, more or less violent, in those portions of the body* which were 

 most affected. By one of these, my right arm was paralyzed so com- 

 pletely that I could neither use nor. raise it for several minutes, and I 

 suffered much pain in it at the shoulder-joint for several hours. At 

 half-past twelve, the clouds began to pass away and the phenomena 



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