Chemical Science. 431 



the poles at first feebly augments to a certain degree, beyond 

 which it gradually diminishes, and at last disappears. With 

 a temperature a little lower, however, the extraordinary electricity 

 appears, and the poles resume their power, but in an inverted 

 order, so that the pole at first positively electrified becomes nega- 

 tive, and the negative pole becomes positive. 



These results are detailed at large in M. I'Abbe Haiiy's 

 Traite de Physique. We have taken them from the Annaks de 

 Minei. vi. p. 608. 



15. Electricity of the Atmosphere. — M. Bourdet, an ex-cap- 

 tain in the French service, has described, in a letter, a very sin- 

 gular electrical phenomenon which he witnessed in Poland, Dec. 

 24, 1806. The weather, according to the Poles, had never been 

 milder at that season of the year, no snow had been seen, nor had 

 the usual cold weather of the north, which generally sets in early 

 in that country, then commenced. Rains and storms, however, were 

 frequent. " 1 was," says M. Bourdet, <' with the advanced guard of 

 light cavalry ; the commander gave me an order to halt in the rear 

 and see that my guns were disembarrassed, and then to rejoin, as 

 quickly as possible, the light brigade. In spite of the eflbrts of 

 my men, the guns were not cleared from the marshy ground in 

 which they were entangled, without great labour. We were 

 advancing across the field about nine o'clock in the evening, when 

 a strong gust of wind suddenly arose, (the sun had shone brightly 

 during the day,) and in a few minutes after, the night became so 

 dark, that we could not sec the heads of our horses. The wind 

 blew so violently, that the horses stopped. At that moment the 

 extremity of the hair on their ears became luminous, as well as 

 all the longer hairs on their bodies, except the locks on their 

 manes and tails. All the metallic extremities of their harness, 

 and all the metallic sharp points of the carriages of our guns, 

 were studded with luminous points, so that one might have sup- 

 posed, had it been spring, that a swarm of glow-worms had 

 covered our horses and guns. Our quarter-master observed that the 

 points of my mustachios were luminous. The same phenomenon 

 was seen on some of the cannoneers, but none of us had our 

 eye-lashes or hair rendered luminous. These lights remained as 

 long as the gust of wind lasted, namely, for three or four minutes. 

 Their colour was a soft violet, and they terminated in a bright 

 white. The horses held their heads high, their cars were erect 

 and moving, their nostrils open and respiring, their manes and 

 tails erected, their fore legs thrown forward, and their hind ones 

 back. Their attitude, in general, w'as that of animals seized with 

 terror. During the time the wind blew, they remained at full 

 -stop, and when feeling the spur, some stood stock still, and others 

 kicked, as if (hoy had been reluctant to a<lvance. When the 

 2G2 



