SCIENTIFIC SUMMARY. 
525 
tends “ less to the distortion of structure than that used by other observers.” 
In this we cannot at all agree with him. It seems to us that the process is 
an exceedingly objectionable one. All tissues — and especially nervous ones — 
contain water in large proportions, intimately associated with the other 
elements ; this would expand during the act of congelation, and so would 
inevitably give rise to many of the ’curious “ cavities ” and “ reservoirs ” which 
the observer records. — Vide Quarterly Journal of Microscopical Science, 
April. 
METALLUEGY AND MINING. 
Constitution of Steel. — It would appear that M. Caron’s researches upon 
this subject, which have already been reported in this Eeview, have been 
favourably considered by the Belgian Academy of Sciences. This scientific 
body has awarded a gold medal to M. Caron for his researches. M. Stas, 
who was one of the Committee appointed to inquire into the merits of M. 
Caron’s essay, made the following comments, proving that he fully coincides 
in the views of M. .Caron : — “ Steel is essentially composed of iron and 
carbon, and owes its qualities or defects to two different causes — the state 
of the carbon in the metal or the nature of the foreign bodies with which 
it is united. Whenever steel is good, its carbon can, under the influence 
of tempering, combine wdth the iron and give a hard brittle metal, which 
the tempering renders supple and elastic. When steel becomes bad, 
after undergoing several heatings, it is due to its carbon having been burnt 
or separated from the iron, and tempering will not regenerate the combina- 
tion. This separation is mainly due to the influence of the foreign bodies, 
more especially silicium. These bodies also give to the metal defects varying 
with their nature and the impurities they contain.” In concluding his 
report, M. Stas passed a very high eulogium upon the labours of M. Caron. 
Action of Sea-water upon Metals and Alloys. — That we are not idle at 
home as to investigations upon the above subject, ample proof is afforded by 
the experiments of Messrs. Calvert and Johnson. From repeated inquiries 
these gentlemen have been led to the following conclusions ; — (1.) The metal 
now most in vogue for ship- building — namely, iron — is that which ‘is most 
readily attacked by sea-water. (2.) This metal is most materially preserved 
from the action of sea- water when coated with zinc, and, therefore, it would 
amply repay ship-builders to employ galvanized iron as a substitute for the 
pure metal. (3.) The extraordinary resistance which lead offers to the action 
of sea-water naturally suggests its use as a preservative to iron vessels against 
the destructive action of that element ; and although pure lead is too soft to 
stand the wear and tear which ships’ bottoms are subject to, still, an alloy of 
lead could be devised to meet the requirements of ship-builders. The 
experiments which led to the foregoing conclusions were thus conducted : — 
Twenty square centimetres of each metal were taken and carefully cleaned, 
in order that the sea- water might have its full effect. Then, two plates of 
each metal were placed in separate glass vessels and immersed in equal 
