1900] MICROSCOPICAL JOURNAL. lOd 



and etch ordinary metals and alloys, and specimens can 

 now be prepared for the microscope in a few minutes. Mr. 

 Stead's work has yielded some unexpected results. In a 

 recent demonstration, pig-iron was shown to have its con- 

 stituents gathered into separate centres, the carbides be- 

 ing in isolated silvery crystals, while the phosphorus and 

 sulphur compounds were each distinctly separated. A 

 brilliantly polished piece of white pig-iron, containing 

 carbon, sulphur and phosphorus, was then heated until it 

 became purple. Under the microscope the constituents 

 were found to have diverse colors, the iron being of a fine 

 sky blue, the carbides an orange color, the phosphides a 

 pale brown yellow, and the sulphides a slaty blue. Thig 

 method of identifying phosphides is a new discovery which 

 will be of great value to iron manufacturers as a simple 

 means of telling whether iron contains phosphorus. The 

 microscope shows that alloys, instead of being homogene- 

 ous, as have been thought, are built up of various crys- 

 tals, and is likely to prove of practical service to metal 

 workers in many ways. — Knowledge. 



Experiments to Determine the Cause and Dissemination of 

 Texas Fever. 



DR. D. E. SAI^MON. 

 [This article shows some of the limitations of microscopy in deal- 

 ing with disease. — Editor.] 



The first step toward revealing the nature of the dis- 

 ease was evidently to determine if it could be inoculated 

 from animal to animal. If this (Question were decided in 

 the affirmative, it would be possible, by continuing the in- 

 oculation experiments, to determine how widely the virus 

 was distributed through the body, and with what secre- 

 tions or excretions it was disseminated by the affected 

 animal. It might also be possible to identify a micro-or- 

 ganism as the essential cause and to study its biology. 



