1826.] Scientific Notices — Miscellaneous. 315 



lighten a superficial examination, but which was found to have 

 a specific gravity of 4-4, It is, therefore, as heavy as some of 

 our ores of copper and iron. We ought to mention that these 

 numbers were given by the Professor rather as approximations 

 than as strictly accurate results, the instrument first constructed 

 not being quite so perfect as he expects by and bye to render it, 

 and his experiments not having been very numerous.— (Scots- 

 man.) 



10. Preservation of Anatomical Preparations. 



Braconnot has applied the persulphate of iron, in consequence 

 of its astringent and antiseptic properties, to the preservation of 

 anatomical preparations. It combines easily with all the humours 

 and soft tissues of animals, and preserves them from putrefaction 

 and insects. A brain, portions of liver, spleen, and lungs, 

 impregnated with this salt, have a long time resisted destruction. 

 Dr. Macartney, of Dublin, covers his preparation jars with a thin 

 plate of Indian rubber varnished* This is superior to lead or 

 bladder, and retains the vapour of alcohol perfectly.— (Dublin 

 Philosophical Journal.) 



1 1 . Local Attractions. 



The Connaissance dcs Tems, 1827, contains an account of 

 Geodetical operations in Italy by the French geographical engi- 

 neers, remarkable for the discordance it exhibits between results 

 deduced from these operations and from astronomical observa- 

 tions. Of the exactness of the survey no doubt can be enter- 

 tained from the recital given, and the astronomical results are 

 founded on the observations of several most able astronomers. 

 The discordances, which in one case amounts to nearly 27'' and 

 in another to 17", are attributed to local deviations of the plumb 

 line, caused by irregular attraction. The matter near the surface 

 at Milan appears to attract the plumb line considerably to the 

 north of the vertical, and that near Remini considerably to 

 the south. — (DubUn Philosophical Journal.) 



12. On the cutting of Steel by soft Iron. 

 By Thomas Kendall, Jun. 



As the subject of cutting steel by soft iron has excited consi- 

 derable attention, and seems not yet to be exhausted, 1 take the 

 hberty to communicate such facts connected with the subject as 

 have come under my own observation, together with some 

 remarks, which are at your disposal. In the cutting ofrevolving 

 iron by tempered steel, experience proves that there is a certain 

 velocity beyond which it cannot be well and freely done. Much 

 depends on the purity and state of the iron ; much on the form, 



• See Annals for January, p. 74. 



