2 Dr. GuY^ on Microscopic Sublimates. 



Medicine^ (No. iii, 1858), and in a paper read at a meeting 

 of this Society; and published in your Journal, in 1861. At 

 that time, and till within a few months of this date, 1 limited 

 the application of this method of procedure to the volatile 

 metals, mercury, arsenic, cadmium, selenium, tellurium, and 

 some of their salts, and to a few other volatile matters, such 

 as the muriate of ammonia, camphor, and sulphur. It was 

 no part of my plan to test these sublimates by reagents ; and 

 the use of the microscope was restricted to the examination 

 of the sublimates themselves. But in the year 1864, Dr. 

 Helwig, of Mayence, made the unexpected discovery that the 

 alkaloids when submitted to this treatment could be made to 

 yield sublimates ; and in 1865, he published a work under 

 the title of " The Microscope in Toxicology,"* in which the 

 sublimates of the alkaloids and their reactions are minutely 

 described, and largely illustrated by photo-micrographs. This 

 work I have recently made the subject of serious study ; and in 

 verifying its statements, have been led to transgress its 

 limits, and have found that the method of procedure first 

 suggested for such mineral substances as arsenic and mer- 

 cury, and their salts, and then extended by Helwig to the 

 alkaloids, strychnine, morphine, veratrine, &c., might be still 

 further extended to such animal products as the constituents 

 of the urine and the stains of blood, and indeed to all vola- 

 tile and decomposable matters, whether of vegetable or of 

 animal origin. A few specimens of sublimed alkaloids were 

 shown^ a few months ago, at a soiree of the Pharmaceutical 

 Society, and a larger number, with sublimates of blood-stains, 

 and choice specimens of arsenious acid and corrosive subli- 

 mate, at a subsequent meeting at the College of Physicians ; 

 while an account of several investigations bearing on the 

 subject, which I have carried on during the last six months, 

 has appeared in five successive numbers of the ' Pharmaceu- 

 tical Journal.^ Still, I believe myself justified in speaking of 

 the whole subject of microscopic sublimates as novel, though 

 no longer new. 



2. Largeness of scope. — Heat, as applied by the flame of 

 the spirit lamp to the reduction-tube or platinum foil, is one 

 of the chemist^s familiar tests and means of identifying 

 arsenious acid and corrosive sublimate ; and it has long sup- 

 plied an element in the description of the alkaloids and other 



* ' Das IVIikroskop in der Toxikologie.' "Beitrjige zur mikroskopischeu 

 und mikrochemischen Diagnostik der wichtigsten Metall— uud Pflanzengifte, 

 fiir Gerichtsarzte, gerichtliclie Chemikerund Pbarmaceuten, mit einem Atlas 

 photographirter mikroskopischer Praparate," von Dr. A. Helwig, pract. 

 Arzte und Grossherzoglicli Hessischem Kreiswundarzte in Mainz. 1865. 



