12 Messrs. L. Hill and M. Greenwood, Jun. [Oct. 1, 
When dried at 105° C., the substance loses only two molecules of water of crystal- 
lisation :— | 
06120 gramme air-dried substance lost at 105° C. 0:0640 gramme H,O = 10°46 per cent. 
Calculated for C,H,O,NaSb.2H,O. H,O = 10°49 per cent. 
The remaining half molecule is subsequently lost in vacuo over sulphuric acid. 
0°6120 gramme substance dried at 105° C. then lost 7m vacuo over sulphuric acid 
00110 gramme H,O. Total loss = 12°25 per cent. 
On exposure to air, the two and a half molecules of water of crystallisation are again 
taken up, but the salt does not deliquesce. 
0°5370 gramme substance dried <2 vacuo over sulphuric acid, on exposure to air 
ncreased in weight to 0°6066 gramme. 
The Influence of Increased Barometric Pressure on Man. 
No. 4.—The Relation of Age and Body Weight to Decom- 
pression Lffects. 
By Leonarp Hitt, F.R.S., and M. GREENwooD, Jun., M.R.CS. 
(Received October 1,—Read December 5, 1907.) 
Statistics of caissons and diving works tend to suggest that the percentage 
number of men affected injuriously by exposure to compressed air increases 
with age. 
Pol and Watelle (1) record that men between 18 and 26 stood the work 
best, and that of the 25 men dismissed for illness from the works under their 
inspection, 19 were over 40 years old, 5 over 30, and 1 over 28 years. 
Catsaras(2) investigated 62 instances of paralysis among sponge divers, 
and we find that, of these, 33 were over 30 years old, 17 over 25, 11 over 20, 
and 1 over 19. These men dived about 140 feet, spent about 10 minutes 
below, and were decompressed in about one minute. 
_ Evidently this variation might depend on—(i) the actual age difference ; 
(ii) on an increase in mean body weight with age; (111) on a combination of 
(i) and (ii); (iv) it might be purely random. We cannot absolutely exclude 
(iv) in the instance of caisson works unless we know the total number of 
men at each age employed, figures which do not seem to be available. 
Snell (3) gives the following table (Table I) of his observations, made at the 
Blackwall Tunnel works. 
Unfortunately, column 2 gives not the total number employed, but only 
those who submitted themselves to medical inspection, which was not, at 
first, compulsory. . | 
