62 J. A. EWING AND J. G. MACGREGOR ON THE 
SULPHATE OF ZINC. 




i Tif Ue IV. aL Me III. IY. 
Ratio fst | Density at |Reistenes 2] sistance at | Rates| Density a |Resstaes in| sttane at 
solution. > B. A. Units. BA Uris: solution. : B. A. Units. ene ntis: 
1to 40 1:0140 8200 182°9 Ito 1:5 1:270 1280 28°5 
ed) 1:0187 6300 140°5 Se eye 12891 1270 28°3 min. 
1, AY 10278 4980 aa eetca Gil 1°2895 1280 28°5 
1a 1:0540 2860 633. Hines 1:2987 1288 28-7 
Le ae7 1:0760 2280 50°8 1, Valea) 3288 1310 29°2 
W 55 8) 11019 1890 42°1 Fe | 1°3530 1390 31°0 
ils. 8} 1:1582 1510 33°7 1 e-rapeb es ) 1°4053 1440 By ae | 
Wis, SRB) 1:1845 1440 By | 1,, 763 Tate 1500 33°4 
leg 1:2186 1360 30°3 1 ai 
Le 1-626 1°2562 1310 29°2 Saturated a sas Gx 


It will be seen that the conductivity reaches its maximum when the density 
is 1°2891, a solution which may be prepared by dissolving °735 parts of salt in 
1 of water. BrcQueEret referred to this point, but did not determine it, as he 
only tested three solutions, none of which were at all near it. We have recently 
found that Paatzow made an approximate determination of this point (Pogg. 
Ann., cxxxvi., 1869). He places it near the solution of 1 part of salt to 1 of 

water, a considerably different position from that to which we have assigned it. 
This discrepancy may be due, and probably is due, to the fact that Paatzow’s 
measurements were made at a temperature of 23° C., a very much higher one 
than ours. We regret that we have not had time to investigate the influence 
