

TRANSACTIONS OF THE SECTIONS. 39 
hydrochloric acid, and evaporating to dryness, repeating the operations if necessary, 
of till the above ingredients are decomposed. In the case of kelp, the following is 
an outline of the mode of procedure :—A known weight is exhausted with water in 
the usual manner, and the several liquors, being mixed, are concentrated by evapora- 
tion, and set aside to crystallize. The mother-liquor is decanted and slightly super- 
saturated with hydrochloric acid, boiled and filtered. The filtrate is then evaporated 
completely to dryness, a little carbonate of soda being added towards the conclusion, 
if it be found that the hydrochloric acid is in such excess as to affect the iodide. 
This will be indicated by the liberation of iodine, and by the solution acquiring a dark 
colour. The dry residue is digested in a small quantity of cold water and filtered. 
The solution is then tested for the presence of the substances before named, when, if 
pure, it is transferred (wholly or in part, according to the quantity of kelp operated 
upon) to the alkalimeter, and subsequently dropped into the prepared solution of 
bichromate of potash and hydrochloric acid, as previously described. If however it 
should still contain any sulphite, hyposulphite, &c., the treatment with hydrochloric 
acid isrepeated. It has been found that the extraction of the iodide from the residue 
by means of alcohol answers very well when the removal of the incompatibie matters 
is attended with difficulty. The quantity of iodine in kelp is proportionately small, 
and of course subject to extensive variation. The amount extracted on the large scale 
from “drift-weed kelp” varies from 5 to 12 lbs. per ton, though larger quantities are 
said to have been obtained. From cut-weed kelp not more than 2 to 3lbs. per ton 
have been extracted; and it is easy to conceive that the produce will be variable 
when these two kinds of kelp are mixed together. Not less therefore than 2 lbs. of 
drift-weed kelp should be operated upon, and in the case of cut-weed kelp, it will be 
advisable to use only 5 grs. of bichromate of potash in place of 10 grs. 
The method of testing kelp-liquors is evident from the above outline of the mode of 
operating upon kelp itself. 
On the Oil of the Sun-Fish. By Professor E. Ronaups, PA.D., FCS. 
On the application of certain Optical Phenomena to Chemistry. 
By Professor G. G. Stoxss, M.A., F.R.S. 
On the Koh-t-Noor Diamond. By Professor Tennant, F.GS. 
At the last Meeting of the British Association, Dr. Beke read a paper on the dia- 
mond slab supposed to have been cut from the Koh-i-Noor, and stated, that “at the 
captute of Coochan, there was found among the jewels of the harem of Reeza Kooli 
Khan, the chief of that place, a large diamond slab, supposed to have been cut from 
one side of the Koh-i-Noor, the great Indian diamond now in the possession of Her 
Majesty. It weighed about 130 carats, showed the marks of cutting on the flat and 
largest side, and appeared to correspond in size with the Koh-i-Noor.’’ Professor 
Tennant was induced to record his opinion of the probability of this being correct. 
He had made models in fluor spar and afterwards broken them, and obtained speci- 
mens which would correspond in eleavage, weight and size with the Koh-i-Noor. By 
this means he was enabled to include the piece described by Dr. Beke, and pro- 
bably the large Russian diamond, as forming altogether but portions of one large 
diamond. The diamond belongs to the tessular crystalline system; it yields readily 
to cleavage in four directions, parallel to the planes of the regular octahedron. Two 
of the largest planes of the Koh-i-Noor, when exhibited in the Crystal Palace, were 
cleavage planes; one of them had not been’polished. This proved the specimen to 
be not a third of the weight of the original crystal, which he believed to have been a 
rhombic dodecahedron, and if slightly elongated, which is a common form of the 
diamond, would agree with Tavernier’s description of it, bearing some resemblance to 
an egg. 
On Chemical Combination ; and on the Amount of Heat produced by the 
Combination of several Metals with Oxygen. By Tuomas Woops, M.D. 
The author endeavoured to show that in chemical combination no action different 
from that which takes place in simple bodies when expanding or contracting, when 
