52 
Proceedings of the Royal Society 
owing to the exhaustive investigations of Professor Thomsen of 
Copenhagen, on thermal values. In the paper referred to, the results 
are calculated on the assumption of hydriodic acid evolving 15,000 
heat units for equivalent in aqueous solution. The above num- 
ber is much too high, according to Thomsen’s recent experiments, 
who gave 13,170 as the true number. If my former results are re- 
calculated with the new value for hydriodic acid, the following 
numbers are obtained: — 
Formation of Iodic acid in aqueous solution = 25,000 heat units. 
These results show clearly that the stability of the series in- 
creases as we ascend, and not the reverse, as has been generally 
supposed, from the thermal values obtained by Favre. No known 
series of bodies, therefore, diminishes in stability, or has a regular 
increment of absorption. 
3. On the Ptesemblances which Microscopic Objects in 
Dichroite and Amethyst have to some of the lower forms 
of Organic Life. By J. Scott, Tain. Communicated by 
Professor Kelland. 
When examining with the one inch object-glass of a compound 
microscope some pieces of Strathpeffer Albert coal, I happened to 
place on the stage a crystal of dichroite, and was surprised to 
observe its surface covered with circular impressions. Their 
resemblance to some which I had previously noticed on iron pyrites 
associated with Albertite, led to a further inspection, which showed 
that they were due to globular bodies of various colours distributed 
throughout the crystal in layers parallel to the respective faces. 
By means of sections cut parallel to these faces, I observed that 
the lower side of each layer, namely, that looking towards the 
interior of the crystal, differs essentially in its structural peculi- 
arities from the upper. On that side each object has a conical 
form like a limpet shell, and usually consists of three or four easily 
Chlorine ,, 
Peroxide of chlorine 
Chlorous acid 
Hypochlorous acid 
-18,000 
= - 9,800 
= - 21,000 
= - 28,000 
(Thomsen.) 
