TRANSACTIONS OF SECTION B. 687 



From the foregoing it is evident that the San Raphael coal is one of great 

 interest, heing not only of fair quality as a combustible, but being also available as 

 a source of vanadic acid for industrial purposes, seing that each ton of the mineral, 

 supposing it to be equal to the sample, v?ill produce over 14 lbs. of jnire ash con- 

 taining 4| lbs. of the vanadic pentoxide, of which 3| lbs. may be extracted by 

 simple treatment of the ash with an alkaline liquor, whilst the remainder is of 

 course susceptible of extraction from the insoluble part, as in the case of basic 

 slags of Creusot ('Comptes Rend.,' xcv. 42-44), which contain but 1-5 per cent. 

 In short, the ash of the San Raphael lignite is, so far as my knowledge goes, the 

 richest known material utilisable as a source of vanadium compounds. I have 

 taken steps to obtain information regarding: the carboniferous strata whence my 

 sample of mineral was derived ; the details cannot fail to be of great interest. 

 Meanwhile I have been assured that the seam where explored is about a metre in 

 thickness. The Argentine provinces of Cordoba and San Luis are abeady well 

 known as sources of vanadium minerals, such as vanadinite, dixloizite, and 

 psitlacinite. The province of Mendoza must now be added to the list of localities 

 in the Argentine Republic where vanadium is to be found. 



16. Sewage Precipitation. By Q. Carrington Purvis. 



WEDNESDAY, AUGUST 10. 

 The following Papers and Reports were read : — 



1. Atmiic Weight of Boron. By W. Ramsay, Ph.J)., F.E.S., and 

 Emily Aston, B.Sc. (Lond.) 



We have made a re-determination of the atomic weight of boron by the follow- 

 ing methods : — 



1 . A preliminary re-determlnation of the water of crystallisation in borax. 



2. Conversion of anhydrous sodium borate into sodium chloride, by distillation 

 of the borax with hydrochloric acid and methyl alcohol, and weighing the result- 

 ing sodium chloride. 



Pure borax was prepared from pure boracic acid and pure soda. It was found 

 to be an efflorescent substance, so the estimation of the water of crystallisation is 

 hardly a method suited for an atomic weight determination. We made our ex- 

 j)eriments upon it during damp weather, so that the loss of water that it under- 

 went was not great. 



Method I. 



Determination of the water of crystallisation in borax, NaoB,0 J0II,O. 



A weighed quantity of borax, generally about 6 grams, was placed in a plati- 

 num dish, and heated 'in an air-bath at a temperature of about^90-I10° C. for 

 some time ; the temperature was gradually raised to about 350° C. ; the borax 

 swelled up very much, and in some cases there was loss by spurting ; the dish was 

 then taken out of the air-bath, and the borax fused over the blowpipe ; it was 

 then allowed to cool in a desiccator, and the fused borax weighed. The loss in 

 weight gave the percentage of water, from which the atomic weight was calcu- 

 lated. 



The results are given in Table I. The mean atomic weight obtained is 10-921 



for boron. 



The atomic weights used in the calculations are: 11 = 1-008; = 16; 

 Na = 2305; 01 = 35-45; Ag = 107 92. 



