236 THE AMEKICAN MONTHLY [October, 



NOTES ON TECHNIQUE. 



Detection of Blood-Stains. — Since Professor G. G. Stokes and 

 others first called attention to the peculiar absorption spectrum yielded 

 by blood, the spectroscope has been often employed to detect blood- 

 stains. The latest essays in this direction are alluded to in Dr. Cran- 

 stoun Charles' excellent Annual Report on Medical Chemistry. He 

 tells us Linossier finds that the most sensitive spectroscopic reaction of 

 blood is that given by reduced hsematin. 



The blood-stain is dissolved in water and examined for the spectrum 

 of oxy haemoglobin. A drop of freshly prepared hyposulphite of soda 

 is now added, when the spectrum of haemoglobin appears at once ; fin- 

 ally, a couple of drops of a concentrated solution of soda are added, 

 which decomposes the haemoglobin into globulin and reduced haematin. 

 the spectrum of the latter consisting of two absorption bands situated 

 between D and b, the left one lying midway between D and E, and 

 being well marked ; indeed, this intense band is the only one to be 

 distinctly observed in dilute solutions, and it ought to disappear if the 

 solution is heated to 50 C, without stirring or agitation, and reappear 

 on cooling ; it ought further to disappear when shaken in the air, and 

 reappear on the addition of a drop of hyposulphite of soda. This test 

 applies even to putrid blood. Should the blood-stain have become 

 insoluble in water, we are directed to dissolve it in ammonia, and 

 reduce by adding one or two drops of a solution of ferrous sulphate 

 and tartaric acid. — The Dosimetric Medical Review, July, i8Sg. 



American Objectives. — Dr. Pelletan, editor of the Journal de 

 Micrographie, says : " Doctor Detmei-s reaffirms that the best German 

 objectives are in no way superior to the best efforts of the American 

 opticians. I have said in a former article how thoroughly tenable I 

 hold this assertion to be, and declared that I agreed in it completely. 

 I believe that I was first to declare (a long time ago) that poor Robert 

 B. Tolles, so unhappy in his too short career, so long misundei - stood in 

 his own country and ignored abroad, was the greatest optician in the 

 world, and I am prepared now to prove that he has never yet been sur- 

 passed. I therefore desire to associate myself with Dr. Detmers in the 

 words in which he closes his communication." 



To the above Dr. W. J. Lewis adds his views : 



" Strong words these, but while agreeing with Dr. Pelletan (and Dr. 

 Detmers) in all that he can say concerning the excellence of the work 

 of Tolles, I believe that the elder Spencer, who soon followed his friend 

 Tolles to the Silent Land, was as good as Tolles. I believe further 

 that his son Herbert Spencer is second to no living optician ; that Gund- 

 lach has produced and is producing objectives the excellencies of which 

 cannot be duplicated in Europe to-day, and that for certain grades of 

 objectives those of Bausch & Lomb are absolutely incomparable. 

 American opticians have absolutely nothing to fear in competitive con- 

 tests so far as excellence of work goes with any in the world. I have 

 no patience, therefore, with Americans who are sending abroad for 

 microscopes and objectives. They can get better at home for the same 

 expenditure of money." — St. Louis Medical and Surgical Journal, 

 July, i88q. 



