Intelligence and Miscellaneous Articles. 295 



If the recently-precipitated and washed oxide be examined by the 

 microscope, it ^vill be seen to be composed of amorphous globules, 

 amon- which no crystals are perceptible; on the contrary, the pre- 

 cipitate which has been long kept under water appears to be entirely 

 crystalline : the small fragments of crystals are of a deep yellow 

 colour and slightly translucent. The author states that he is not 

 aware of the time required to convert the amorphous into the cry- 

 stalline peroxide ; but the precipitates on which he made his expe- 

 riments had been prepared more than two years previously. He 

 thinks however, that the transformation had taken place for a con- 

 siderable time ; for he remembers to have remarked that in six 

 months the preoipitate had altered in appearance and become more 

 compact. The hydrate, moreover, in assuming the crystalhne form, 

 loses half the water which it contained; the formula ot the precipi- 

 tate which has undergone this change is 2Fe;- 0' + 3HO. 



The difficulty then which attends the solution of hydrated peroxide 

 of iron that has been long kept under water, depends upon two causes 

 the crystalline form and partial dehydration. It results from_ what has 

 been above stated, that the peroxide of iron, in order that it may be 

 dissolved by the acids named, and weak acids m general, ought to 

 be employed so,^i after precipitation. It is pi-obably not mdifferent 

 that the peroxide of iron employed as an antidote to arsenic should 

 be recently-precipitated ; at all events, preference ought to be given 

 to recently.precipitated oxide, and it will be proper to renew it every 

 six months, or annually. It is not requisite entirely to reject the 

 hydrate which has been kept ; it may be dissolved in hydrochlonc 

 acid and again precipitated by ammonia.~7oMr«. de Pharm. et de 

 Ch., Fevrier 1847. 



ON VILLEMITE. BY MM. DELESSE AND DESCLOIZEAUX. 

 The mineralogical collection of M. De Dree contains ^brownish 

 silicate of zinc from Franklin, New Jersey, United States. It appears 

 to have been already analysed by MM. Vanuxem and Keating, who 

 have referred it to the villemite of Levy ; but as it difters much m 

 appearance from the villemite found in Europe and as its analysis 

 does not agree with that of a mineral analysed by Dr. Thomson. 

 and identical as to its physical properties, and trom the same locahty 

 MM Delesse and Descloizeaux thought it would be interesting to 

 make a comparative examination of the two minerals. 



The villemite which MM. Delesse and Descloizeaux^ analysed was 

 from the zinc mines of Vieille-Montague near Aix-la-Chapelle : it is 

 in small crystals, of a light rose colour, and has the form ot a regular 

 hexagonal prism, terminated by an obtuse rhomb ot an angle ot 12b 

 30', as described by Levy and Phillips. These crystals were con- 

 tained in the druses of a ferrugmous calamine. ,„•,,. 

 The silicate of zinc from New Jersey was also crystaU.zcd but 

 confusedly «o ; sometimes however the crystals are very well de- 

 fined, and they are referable, both as to form and cleavage, to the 

 viUenutc of Levy. The angles are the same ; the cleavages perpen- 



