Mordant for Crystallized Tin^ — Emotion of Vesuvius. 391 



we gave in our last number, show the path of it to be ellipti- 

 cal; and that it performs its revolution in 194 years. 



11. The Co7inais^a?ice des Terns for 1825, has just made its 

 appearance in this country: as well as the Coimbra Ephemeris 

 for 1823 and 1824'. Bode's Astronomische Jahrhuch for 1825 

 has not yet arrived. The Milan ephemeris is always slow in 

 its progress to this country: the volume even for 1822 is not 

 yet to be procured. ■ 



MORDANT FOR CRYSTALLIZED TIN. 



A celebrated chemist, now retired to cultivate his land (says 

 the Giorn. di Fisica, Dec. II. P. I. p. 217) recommends the 

 following mixture as a mordant for moire metallique on tinned 

 iront, — the crystallized tin of artificers. 



Sulphuric acid diluted with six parts of water, 3 ounces. Ni- 

 tric acid, 1 to 2 drachms. Diluted solution of chlorine, l ounces. 

 Oxalic acid, 1 to 2 scruples. The juice of an orange. 



The brilliant ground may be darkened at pleasure. An ad- 

 dition of ammonia to the liquor makes it dai'ker, and more so 

 a little sulphate or acetate of copper. After the action of the 

 mordant it may again be altered : by carbonate of potash the 

 brilliancy is softened, and raised by caustic potash (either must 

 be well diluted with water). 



If a tinned iron of a fine grain is wanted, the moi'dant must 

 at first be aj^plied, and then the tinned iron be heated in a 

 furnace till the tin begins to melt ; it is then taken out and 

 sprinkled with fine drops of water. 



ERUPTION OF MOUNT VESUVIUS. 



Naples, October 21. 

 Yesterday, at sunrise, Vesuvius was still tranquil, though 

 for two days the water of the surrounding wells had entirely 

 disappeared: but a few seconds after twelve o'clock, smoke, 

 mixed with lava as usual, began to appear. About two o'clock 

 a dreadful internal noise was heard throughout the whole 

 neighbourhood, and the noise contiimed to increase until mid- 

 night. In fine, about halt-past three o'clock a terrible explo- 

 sion took jilace from the upper cone, preceded by repeated 

 shocks and internal howlings from the mountain. 



The shocks increased gradually to sunrise, and about two 

 hours after sunrise a torrent of lava about a mile broad was 

 perceived, and extending as far as a mile and a half between 

 the Casa de la Favorite and Ilcsina. The terror of the pea- 

 sants, and of the people who at this season occujiy their coun- 

 try-houses, was so great, that the road from Portici to Naples 

 was filled with carriages conveying lluniiies and valuables iiom 

 the scene of danger. According to the latest accounts, the 

 mountain was undergoing great convulsions, and though the 

 weather was serene, a thick cloud of ashes and stones dnrkencd 



all 



