58 PKOr. EDWARD HCLL^ LL.D.^ F.li.S., F.G.S., ON 



and yet it is clearly seen how they are formed. It is very easy to 

 find that some of the very substances obtained from these beds are 

 obtained from sea water. Undoubtedly there are very minute traces 

 in all sea water of boron components, which is found crystallised 

 in the form of boro natro calcite in these nitre beds. You must 

 evaporate an enormous quantity of sea water to get evidence of 

 these substances. Boron you can find with the aid of the 

 spectroscope, but iodine, which also abounds in these beds, is 

 extremely difficult to obtain from salt water ; but the pro- 

 cesses of certain sea weeds, of obtaining it, for the physical 

 requirements of the plant come to our aid, and it was first dis- 

 covered from the ashes of these sea weeds, which contain a con- 

 siderable quantity. I believe the more you study the chemistry of 

 sea weeds the more confidence you. will have in the value of this 

 admirable paper. 



Rev. F. A. Walker, D.D., F.L.S. — There are two points upon 

 which I should be glad to be permitted to ask for information. 

 First : — Is it not a fact that certain seas do very greatly differ 

 from one another in amount of salinity ? the waters round the 

 Channel Islands are said to be very salt. Secondly : — Is it the 

 case that waters at a great depth down, say one mile or more, 

 differ in their respective degree of salinity from the surface 

 waters ? wo aid their smaller proportion of salinity tend to account 

 for the total absence or great scarcity of organic life at a 

 considerable depth, or is this absence or scarcity solely attri- 

 butable to the absence of light at a great depth ? 



The Chairman. — There is a theory that the globe was once 

 incandescent and probably surrounded by a quantity of acid vapour 

 called carbon-dioxide, and chlorine vapour especially ; if that theory 

 be true does not Professor Hull think that the chlorine vapour and 

 the sodium vapour would have been present and have united 

 themselves, and to the union of these two vapours the immense 

 supply which we have of chloride vapour may be due. 



The Author. — Although the speakers are few they have given 

 me enough to do if I am to answer their questions. But I am 

 rather disappointed that I have had no what I may call downright 

 opponent to meet. 



The Chairman. — I think you cannot expect anybody to criticise 

 so convincing a paper. 



The Author, — Then I will, "with the best grace I can, give my 



