Table X.
Results of a Rough Attempt to Gauge Applicability of the Method of Right and Wrong Causes to Smell.
| SUBJECT—K.SUBSTANCE—ETHYL BUTYRATE | ||||||||||
| Change. | Correct judgments of direction. | Incorrect judgments of direction. | Failures to note change or to distinguish its direction. | Total number of cases. | Change. | Correct judgments of direction. | Incorrect judgments of direction. | Failures to note change or to distinguish its direction. | Total number of cases. | |
| MM. | MM. | |||||||||
| 20 to 30 | 95 | 46 | 11 | 152 | 40 to 60 | 100 | 35 | 6 | 141 | |
| 20 to 10 | 115 | 27 | 6 | 148 | 60 to 40 | 106 | 29 | 5 | 140 | |
We see that here again the number of mistakes was very large. yet these were the last experiments made with K., who had worked for us twice a week throughout the year, and who had used butyric ether successfully in experiments by the method of just noticeable differences. He was, however, very tired at the time these last experiments were made. The second stimulus still is more often mistakenly taken for the weaker than for the stronger, showing that in these experiments also exhaustion outweighed adhesion and the time-error put together. (The tube was cleaned after every eight comparisons.)
Summary and Conclusion.
In beginning our investigations, we saw that we could not isolate simple olfactory qualities, and that an attempt to prove Weber’s law for smell was justified only by the assumption that it might apply to fusions. We also saw that the fact that some olfactory qualities show but few grades of intensity pointed to a rise towards the terminal intensity by geometrical progression. Although Zwaardemaker explains the fact partly by the supposition that different smells have different difference-limina, we believe that two smells with the same difference-limen may exhaust the human sense-organ with very unequal degrees of rapidity, so that one may reach the terminal intensity much sooner than the other.
Aside from the condition of the sense-organ, the intensity of a smell depends (1) on the amount of odorous surface exposed to the air, (2) on the time that it is exposed, (3) on the condition of the air in regard to temperature, moisture, etc., which controls the rate of evaporation, (4) on the diffusion-rate of the
