234 Intelligence and Miscellaneous Articles. 



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lime after that I perceived the arch to have become double j by look- 

 ing more frequently I found this appearance to arise from another 

 arch which was rising above the former, and which after attaining a 

 considerable altitude became irregular in form and disappeared, as 

 well as some other irregular appearances. I noticed the first arch 

 during about an hour and a half, and though it was often very faint, 

 and had almost entirely disappeared, yet when it became bright again, 

 it always had very nearly the same altitude as at first: I, however, 

 sometimes believed it to be a little less if at all different. 



The next evening when 1 had arrived on the high ground of Stan- 

 edge, between Huddersfield and Oldham, there was a promise of a 

 fine display, but the sky became immediately densely overcast, so that 

 no after-opportunity of observing occurred. The appearance on this 

 occasion was different to any I had before seen j the sky in the mag- 

 netic north appeared thickly covered to a considerable height with 

 minute fleecy clouds of bright auroral light ; this uncommon appear- 

 ance made me regret having arrived within the influence of the cloudy 

 atmosphere of Lancashire. I found that the evening of the 21st of 

 December had also been cloudy in the neighbourhood of Manchester. 



ANALYSIS OF GUMS. 



In our Number for September last, we gave the analyses of several 

 gums by M. Guerin; we now continue them. 



Cherry-tree Gum. Specific gravity 1-475, colourless or coloured 

 like gum arabic j it is in rounded pieces of various sizes, like those 

 of gum Senegal, or stalactitic. It frequently contains fragments of 

 wood in its interior ; reddens litmus-paper, and has sometimes an 

 acid taste. Heat, light and chlorine act upon it as they do upon gum 

 arabic ; and the action of alcohol, and of sulphuric and nitric acids, 

 is also similar. When pieces of this gum are put into cold water, 

 they swell and partially dissolve only, whatever may be the quantity 

 of water ; but by boiling for some hours they dissolve perfectly. 

 According to Dr. Thomson, alcohol occasions no precipitation in 

 cherry-tree gum, but M. Guerin asserts that precipitation always takes 

 place. 



One hundred parts cherry-tree gum heated with 400 parts of nitric 

 acid, yielded 15-54 parts of mucic acid and oxalic acid. By analysis 

 it yielded — 



Arabin 52-10 and Carbon 43*69 



Cerasin 34*90 — Oxygen 50-08 



Water 1 2-00 — Hydrogen . . 06-23 



Ashes 1 • 



100*00 



100-00 

 The ashes contain the same substances as those of gum arabic, except 

 sulphate of potash. 



M. Guerin prepares cerasin by exposing one part of cherry-tree 

 gum to the action of 400 parts of water for twelve hours at the tem- 

 perature of 65° Fahr. The mixture is to be frequently stirred, and 

 the water is to be poured off, and the same quantity again added ; this 



