280 KUNKEL: FACTORS INFLUENCING TOXICITY OF 
Ammonium chloride and calcium chloride are most toxic in lactose - 
and least toxic in glucose. Barium chloride, however, is least 
toxic in lactose and most toxic in glucose and starch. Cupric 
chloride, ferric chloride and cobaltous chloride are most toxic in 
lactose. Zinc chloride and mercuric chloride are most toxic in 
starch. Cadmium chloride is most toxic in saccharose. None of 
the chlorides of the alkali or alkali earth metals, but all of the 
chlorides of the heavy metals are least toxic in’ peptone media. 
In lactose media, ferric chloride is more toxic than any of the other 
chlorides; in glucose media, cobaltous chloride is most toxic; in 
starch, peptone and saccharose media, mercuric chloride and 
cadmium chloride are most toxic. Potassium chloride in all of 
the media used is the least toxic of all of the salts tested, except 
sodium chloride in a starch medium. Potassium chloride in 
saccharose is less toxic, and mercuric chloride in starch is more toxic 
than any of the other salts in any of the other media. Reading 
from right to left in Table XII, one sees the increasing toxicity 
of the different salts. The arrangement of the salts in the order 
of their toxicity is different for each of the five different kinds of 
media. 
In order to obtain evidence relative to the number of free ions 
in the various media containing limit concentrations of the same 
salt, a number of tests were made of the electrical resistances of 
the different media. The results of some of these tests are given 
in Table XIII. 
TABLE XIII 
THE ELECTRICAL RESISTANCE OF SOME OF THE MEDIA 
G.M, | Resist- | _G.M. | Resist- | G.N esist- | G.M. | Resist- 
Medium | Conc, “sf ance in | Cone, of | ance in Fase ‘of | ance in | Conc. of | ance in 
| FeCly | Ohms | CuCl, | Ohms | CdCl, | Ohms | HgCl, | Ohms 
Saccharose....| .oooro | 3:700 .00090 | 8,900 | .00006 | 6,500 | .00006 | 14,400 
Glacose. i458 O000IO | 4,900 | .00080 | 10,100 | .00020 | 5,000 |.00010 | 6,900 
Lactose... i... _-00001 5,600 | .00003 .0OOOIO | 7,100 '00002 & 12,500 
pena a F(a: Sa ln .00080 | 4,200 .00045 | 1,600 |.00050 | 1,200 
Peptone...... -03500 | 10 | .02000 97 |.00500 | 160 | .00200 an 200 
The tests of electrical resistance were made by means of the 
Wheatstone bridge method, a Freas electrolytic cell being used. 
The resistances shown by five per cent. solutions of the organic 
substances used have already been given. Table XIII shows in a 
igi cee? 
