66 ANALYSIS OF THE AIR IN ROOMS WHERE THE PAPER 10,000 and below 20,000 population at the last census, HANGINGS CONTAINED ARSENICAL COLORS.-Hamberg 45 possessed no qualified representation of homoalludes to the well-known fact that observations have opathy at all, and twelve other towns had only one already shown the danger of breathing the air of each; of the towns between 20,000 and 50,000 popurooms where arsenical papers are used. The way in lation, no less than 38 had no resident homœopathist which such poison operates has been variously ex-14 of them had only one each, and 5 other only plained by different observers. Some have supposed two each; of the towns between 50,000 and 100,000, that the fine particles of coloring matter became sepa- 9 had no homeopathic physician, 7 had only one rated from the paper, and, floating in the air, are in- cach, and 6 others had only two each; while there haled with the breath. Chemists have been at variance, were, and are actually, 4 towns above the 100,000 limit some finding arsenical gases in the air of such rooms, in which no homeopathist has settled." and others arriving at negative results. Hamberg's The Review further says. Neither can we xperiments were made in a room where the color em- feel satisfied that our hospitals and dispensaries do at ployed was Schweinfurt green. all what they might do in the way of influencing third and fourth years' students. What has London done in this matter with its hospital of sixty beds? What has Birmingham with its well-tried staff and influential committee? What have the Liverpool dispensaries, which admit their 10,000 or 12,000 cases a year? It is not from these places that our recruits have come or are coming.... The local influence of these institutions on the members of the profession, and on the students in our metropolitan and provincial schools, is practically nil." His apparatus was as follows: a. A U-shaped tube for the reception of the dust. b. Three U-shaped tubes, filled with cotton, to completely separate the solid particles of arsenic from the air. c. Two bulb apparatuses, containing a solution of nitrate of silver, to collect any arsenic which might be dissolved in the air. d. Two gasometers of fourteen litres' capacity, alternately filled with water, to establish an aerial current. The air was conducted through this system of tubes from the 16th July to the 16th Aug. of 1873. The quantity of air thus examined amounted to 2,160 litres. In the course of the experiment the solution of nitrate of silver gradually deposited a black precipitate, resembling the arsenite of silver, and after the removal of the silver by nitric acid, the characteristic arsenical ring was obtained by the Berzelius-Marsh apparatus. The author concluded from these experiments that arsenic was present in the air, and probably under the form of arseniuretted hydrogen.-Nord. Med, Ark., vi., 1. 1874. A MODEL ADVERTISEMENT.-A recent Journal-not of the regular school-contains a long advertisement of a celebrated practitioner, from which the following extract is taken: Have yeez pains in yer bones, or a botherin' ache Have yeez vertrebral twists in the sphine av yer back? Be me sowl! But I'll bring all yer woes to complation; ACTION OF IODIDE OF POTASSIUM UPON THE BLOOD. The reactions of the iodide of potassium, when administered medicinally, are thus described: In the stomach the iodide either undergoes no change, the elements of ordinary articles of food being incapable of decomposing it, or else by means of the chlorine hydriodic acid is formed, by which the ultimate reactions are not modified. Entering the circulation in an exceedingly dilute state, the iodide of potassium is at once decomposed by the superabundant carbonic acid into free iodine and carbonate of potassa. Now the iodine will have the greatest affinity for those substances in the blood with which it makes the most complex combinations, this affinity being most intense at the moment of the iodine becoming free. Therefore, of these substances in the blood those first acted upon would be the "miasmatic matters and ferments," next to these the fibrinous and then the albuminous substances, and last of all, the fats. The iodine acts upon these substances by virtue of its disposition to take the place of their component hydrogen. It, however, does not form permanent compounds with them, but, having broken up their chemical union, facilitates their oxidation in the oxygen of the blood. The free hydrogen combines with an equivalent of iodine, forming hydriodic acid, which is in turn attacked by the oxygen, iodine is again eliminated, and so the process is continued. On the other hand, the other component of the iodide of potassium undergoes changes which supplement the action of the iodine. As the compound is decomposed the potash is changed into the hyperoxide of potassium, the only oxygen compound upon which the iodine does not act. Here we have, besides the iodine, a powerful decomposing agent, which, by its strong oxidizing effect upon organic substances, assists the consumption of the blood elements. The hyperoxide is reduced to potassium, which again combines with carbonic acid, and carbonate of potassa is produced as at first. SLOW PROGRESS OF HOMEOPATHY IN GREAT BRITAIN. The Medical Press and Circular notices a leadHence the action of the iodide of potassium depends ing article in the Homeopathic Review, in which the upon the decomposing effect of free iodine upon the latter laments over the unattractiveness of the homo- substances contained in the blood, and their oxidation opathic practice, and makes an appeal to its readers and consumption by the hyperoxide of potassium to unite in seducing, if possible, the rising generation" a result," the writer observes, "which is confirmed of the medical profession. The Review makes the by clinical experience."-Prof. Kammerer, Virchow's statement that of the towns in England above | Archiv, 1874, and Memorabilien, xix., 4. Original Communications. to the right and to the left, they disperse, and this we call the refraction of rays. But we witness another and more interesting phenomenon. The white rays in passing through the prism are decomposed, broken THE IMPORTANCE OF THE SPECTRO-up in a number of beautiful tints, arranged in never SCOPE IN FORENSIC CASES. changing order, presenting red, orange, yellow, green, blue, and violet. This prismatic band we call a spec A PAPER READ BEFORE THE MEDICO-LEGAL SOCIETY trum. We distinguish between an interrupted and a OF NEW YORK, APRIL, 1874. BY S. WATERMAN, M.D., NEW YORK. MR. PRESIDENT AND GENTLEMEN:-No sooner were the brilliant discoveries, by the aid of the spectroscope, in chemistry and astronomy made known, than the attention of scientific and professional men was directed to the inquiry, Whether the marvellous analytical powers of this instrument could not also be employed in the service of medicine? This inquiry, upon whose solution some of the best minds of the continent were employed, has given a highly satisfactory and affirmative answer, and its adaptation to physiological research will furnish us the material for this evening's consideration. continued spectrum. When artificial light is passed Newton, although he examined this subject in all its bearings, never saw the sun lines, because he obtained his spectrum by a round hole in the shutter, and the rays that entered overlapped each other and gave him a diffused spectrum. Wollaston described these lines in 1802, but did not understand their importance. Frauenhofer, a learned optician at Munich, used them first for purposes of measurement in 1814. He designated the most prominent of these lines by the letters of the alphabet, from A to H, and they have since been known as the Frauenhofer lines. Kirchhof left us a map of these lines, a masterpiece of correctness and skill, containing many hundreds of sun lines, and our distinguished Rutherford has photographed them right from the sun himself. The exactness of these two mappings is truly wonderful. Angstroem has given us a map containing many thousands of these lines. The orbs receiving their light from the sun have all these lines in the exact position of the spectrum. Fixed stars, like the resplendent Sirius and others, give quite different arrangement of bright lines, and no black lines at all. Professor Draper, of this city, whose merits in this direction are gratefully acknowledged, has given us a map containing a great number of sun lines, invisible under ordinary circumstances, but which can be made visible under certain favorable conditions; these additional lines are made evident at both the red and violet part of the spectrum, making it of course longer than usual. The human retina is not sensitive to the light waves beyond the red and the violet part of the spectrum. As to the prevalent theory of light, the entire universe is filled with an ethereal substance too subtle to be weighed or measured, in which the "celestial hosts" move without resistance. This ether penetrates all matter, and permeates the innermost atoms. It is in a condition of ceaseless motion; its waves travel with inconceivable velocity, but differ among themselves in degree of velocity and length of each wave. The vibrations least in velocity produce sound, those coming next produce heat, and those having the highest degree of velocity produce light. By means of spectrum analysis we have become acquainted with the laws governing vital processes. By it we have been enabled to lift the curtain, beyond which, since eternity began, those mysterious processes were carried on, which man sought continually to understand, upon which the most strange and conflicting theories prevailed, and which he erroneously thought could never be unravelled. Spectrum analysis has carried us far beyond our former conceptions of the laws of life, health, and death, and forensic medicine comes in for a fair share of the information and benefits thus accumulated from the advance of this science. A few years ago it would have been possible to tell you all that the spectroscope could do in forensic medicine, in the space of half an hour; at this pres-sun lines, and some of the comets give only one or two ent day, the material that has been accumulated could not be exhaustively laid before you in a dozen lectures. Spectral analysis applicable to forensic medicine has become a science by itself, compact, reliable, well-founded, and far-reaching, capable of solving most important legal questions; its application is simple, and it responds to the minutest amount of material. Indeed, it is the extraordinary delicacy and sensitiveness of the spectral test which gives to its application so great a value, and so extensive a scope. It responds distinctly and immediately where the highest magnifying powers of the best microscopes can no longer give us any information; it gives us a valuable reaction for every alteration which blood undergoes when acted upon by physical or chemical agencies; it analyzes the flames of gases, and those of mineral and metal poisons, and unravels the secrets of crime with wonderful alacrity and unimpeachable certainty. By spectral analysis we understand a scientific process in which light, solar or artificial, is made use of to analyze and to demonstrate substances both organic and inorganic. The instrument employed consists of a system of prisms and lenses, by means of which rays of light are broken up into a series of colored tints, called a spectrum, and which offers to the eye all the colors of the rainbow with great beauty and brilliancy. The instrument thus employed is called a spectroscope, or if connected to a microscope, a micro-spectroscope. It is well known what a prism is, and the changes which white light undergoes when passing through it. In the first place the rays, as they pass through a prism, are bent out of their course; they spread fanlike The following eloquent description of the oscillations is given by Dove: "Let us suppose in the midst of a dark room a slender iron bar is suspended and in motion, and there is also an apparatus present by means of which the swinging motions are, continually increased. We enter the room at the moment the bar makes four oscillatory movements per second. Neither ear nor eye gives us any intimation of the presence of the swinging bar. But the movements increase, they reach thirty-two per second. Hark! a deep base sound reaches our ears it rises in pitch with the still increasing oscillations, it passes through all middle stages up to the highest, shrillest note. We are yet full of wonderment, when all sound dies away, and the silence of the grave again surrounds us. But from the region where the sound proceeded we are made sensible of an agreeable warmth the oscillations still increasing we feel the warmth radiating in all directions, in the manner a chimney fire radiates. All is yet dark. The oscillations are now counted by the millions in a second. Behold yonder dawning light; it grows more brilliant, the bar begins to glow, first in red color, then in orange, yellow, green, blue, and violet, until all again sinks back in night and darkness." At this stage you have to count the oscillations by the billions per second. Four hundred and fifty billions are requisite to produce upon the retina the sensation of red light; 500 billions to impress it with orange; 550 billions of oscillations per second will make us sensible to yellow; and 800 billions will impress the retina with violet light. Beyond this our eye is incapacitated to appreciate any increase of oscillations, although, as we have already adverted to, these oscillations exist, and can be made manifest by artificial means. Thus Nature speaks to us in soft and musical notes when near; but when she communicates with us from regions that can be measured only by sun distances, she sends her greetings upon the swift pinions of light. Science has interpreted her cosmic voice, and upon this frail wave the human mind soars upward to the verge of creation. The Frauenhofer lines are of the greatest importance in spectral analysis. Through them we can register any changes we observe in the spectrum, and measure the breadth and the distance of absorption bands from each other. We know now that these lines are produced by various metals in an incandescent condition in the sun, and they can be produced artificially by burning these metals and minerals and comparing the spectra of these vapors. Thus iron, which has a very great number of lines in the sun spectrum, has its most prominent line at E. C, F, and G are peculiar to burning hydrogen. Magnesium yields the Cline, and the H lines, according to Angstroem, are peculiar to calcium. The D line has a historical significance. Burning sodium yields this line. All the progress in spectroscopy is connected with this line. It is the source from which all the wonderful discoveries in solar and terrestrial chemistry had their origin. This line D, called also the sodium line, can be resolved into two or even more lines by the aid of strong light and the combination of several good prisms. The nickel line lies right between them. The coincidence of the D line with that of burning sodium attracted the attention of Professor Kirchhof, of Heidelberg. There was one thing in this coincidence that he could not at first explain. The sun line, as you see here, is a black line; the line of burning sodium is a bright yellow line, as you see here; yet both occupy precisely the same position in the spectrum. One day, whilst examining a flame of burning sodium, he caused the sun rays to pass through the sodium vapor, and lo! he obtained a black line instead of the bright yellow one. He had found the solution of his query. He at once reasoned that there must be burning sodium in the sun, and that there must be a vaporous envelope which absorbed the yellow line and converted it into a black line. Thus, by a most logical and ingenious mode of reasoning, and by a lucky accident, he demonstrated that these lines had a common origin, and that therefore any sun or stars that gave this D line had sodium in an incandescent con dition as one of their constituents. Since then all other black sun lines have been reversed by various scientists. Thus was the foundation laid for the greatest discoveries of the age, and a new and almost infinite vista was opened into the nature and composition of worlds, of which, a quarter of a century ago, we had not the least presentiment. Leaving the historical part necessary to our subject, let me say a few words as to the manner of making examinations by the spectroscope. The solids must be brought to a state of incandescence by heat. We employ for this purpose, where no very great temperature is necessary, a Bunsen burner; where greater heat is necessary we resort to the electric arc, which is capable of fusing every metal known. When metals are thus heated up to an incandescent state, they emit rays of all degrees of refrangibility. If we examine then the evaporating substance spectroscopically, we find peculiarities in the spectrum enabling us to diagnosticate its nature. Fluids are placed before the slit of the spectroscope in suitable glass vessels with plano-parallel walls, or we may use suitable glass tubes. When a ray of light is made to pass through these fluids, ere it impinges upon the prism, we observe an absorption of light in various parts of the spectrum, varying, of course, with the fluid employed; they are called absorption bands. Some colored fluids have one or more bands, changing in position, depth of shading, distinctness of outline, breadth and manner of appearance, furnishing landmarks so distinct and permanent that a recognition of a particular spectrum is made easy, even to the man who is not accustomed to use the spectroscope. As sources of light to examine fluids, we use petroleum or oil flames, and where a maximum light is necessary we may employ the oxygen lime-light, the oxygen spirit-light, and at times, with great advantage, the magnesium light. Gases are examined by means of electric induction sparks. Usually the gases resist the passage of these sparks in their natural state of density. We therefore exhaust a part of the gas with the air-pump. We use thin-bored thermometer tubes, with a bulb on each extremity, into which electrodes of platinum or aluminum are fixed. All other metals would oxidize in the extreme heat generated. The tubes are filled with the gas we desire to examine; the air-pump is then applied until the to part of the ordinary atmospheric pressure is left. In this state of attenuation the gas offers but slight resistance to the passage of the spark, intense heat is generated, and brilliant and beautiful light is emitted, of various colors, changing, of course, with the different gases employed. Thus no known substance can defy the analytical powers of the spectroscope. Every known gas, metal, alkali, or alkaline earth, when thus acted upon by sufficient heat, gives out light peculiar to itself, producing a spectrum differing from the spectrum of any other known substance. Some substances absorb all the colors of the spectrum, with the exception of a single bright band, of which sodium and thallium give an example; others are readily recognized by a spectrum of many bright lines dispersed all over the prismatic field. Of this, barium, cæsium, and rubidium give an example. It is true that the degree of heat employed often modifies the spectra-not indeed as to the position of the characteristic lines and bands of each substance, but as to their number and brilliancy. Thus thallium, for example, gives one green band when evaporated by the heat of a Bunsen burner; but when it is volatilized by the far higher heat of an electric induction spark, we see, in addition, several bright |