Febeuaey 19, 1897.] 



SCIENCE. 



315 



I have ventured into a field without even a 

 decent equipment of knowledge, and that I 

 have altogether failed to understand the real 

 meaning and bearing of the accepted teachings 

 of modern science." "We beg to state gently 

 but firmly that this indictment is strictly cor- 

 rect in all particulars. The author of this 

 screed on gravitation demonstrates conclu- 

 sively: first, that he does not understand the 

 fundamental concept of Newton's law of at- 

 traction; secondly, that he does not know 

 enough of elementary mathematics to apply 

 this law to the simple case of a homogeneous 

 sphere; and, thirdly, that he possesses little of 

 the caution which is born of a knowledge of 

 things physical. He illustrates well the colos- 

 sal impudence of those pseudo-scientists whose 

 equipment consists of formal logic and a facile 

 pen. W. 



SCIENTIFIC JOURNALS. 



PHYSICAL REVIEW, VOL. IV., NO. 4, JANUAEY- 



FEBRUAEY, 1897. 



The Freezing Points of Dilute Aqueous Solu- 

 tions, III.: By E. H. Loomis. This paper is 

 devoted to a continuation of Dr. Loomis' ex- 

 periments on the lowering of the freezing point 

 by dissolved substances. The method is the 

 same as that previously employed. In the 

 present series of experiments the substances 

 tested were chiefly chlorides and phosphates, 

 though several of the more important organic 

 acids were also used. 



Since the substances employed were electro- 

 lytes. Dr. Loomis' results afford a check upon 

 the theory of electrolytic dissociation, osmotic 

 pressure, etc. As in the case of his earlier 

 measurements, the agreement is entirely satis- 

 factory only in few cases. It is well known, 

 however, that the ordinary formula for the low- 

 ing of the freezing point depends upon several 

 assumptions and approximations of a very 

 doubtful character. So that it seems not im- 

 probable that the apparent discrepancies that 

 are brought out by Dr. Loomis' measurements 

 may lead to an improvement in the whole 

 theory. 



A Method for Energy Measurements in the In- 

 fra-red, and the Properties of the Ordinary Bay in 



Quartz for Waves of Great Wave-Length : By E. 

 F. Nichols. This article contains two impor- 

 tant features : first, the description of a new 

 type of instrument for the measurement of infra- 

 red radiation ; and second, the account of meas- 

 urements made with it by which the optical 

 properties of quartz were investigated in the 

 extreme infra-red. 



The instrument used by Professor Nichols is 

 a modified form of the Crookes radiometer. It 

 consists essentially of two excessively small 

 vanes mounted upon a fine quartz fibre and sus- 

 pended in vacuo. The rays to be measured are 

 allowed to fall upon one of the vanes, and a de- 

 flection of the system results. The deflection 

 is measured by means of a light mirror. This 

 form of instrument is found to be much more 

 sensitive than any bolometer heretofore used. 

 More important than its increased sensitiveness 

 is, however, its freedom from the various dis- 

 turbances to which a sensitive bolometer is sub- 

 ject. The radiometer does not depend in its 

 action upon any electric or magnetic forces, and 

 is therefore free from the irregularities which 

 are always present when a sensitive galvanom- 

 eter is used. The instrument is also capable of 

 being more thoroughly protected against outside 

 temperature disturbances. It can hardly be 

 questioned that this instrument will make a 

 considerable advance in our knowledge of infra- 

 red spectra. 



This new type of radiometer was employed 

 in connection with a mirror spectrometer to 

 investigate the reflection and absorption of 

 quartz. For wave-lengths in excess of 4 ,(/ quartz 

 becomes practically opaque with layers of ordi- 

 nary thickness. To investigate the absorption 

 a very thin layer was prepared, the thickness 

 being not more than 18 /-i. SuflBcient energy was 

 transmitted through this film of quartz to be 

 detected, and measurements of absorption were 

 extended to about 8 /i. At that point even this 

 extremely thin layer failed to transmit a meas- 

 urable amount. Numerous well-defined absorp- 

 tion bands were detected between 4 ft and 8 ,". 

 The reflecting power of quartz was measured 

 throughout the same range of wave-lengths by 

 comparison with silver. Making use of the 

 Cauchy formula, the index of refraction was 

 then computed from the observed values of the 



