GILMAN, CHANDLER R. 



GLASS. 



403 



settlers of that region whither they emigrated 

 from New Hampshire. His mother was de- 

 scended from the Puritans, being a daughter of 

 the Rev. Chandler Robhins, the Congregational 

 minister of Plymouth, Mass. Young Gilman 

 was educated at Andover and Harvard College. 

 He studied medicine in the office of Dr. Parrish, 

 of Philadelphia, and graduated at the Univer- 

 sity of Pennsylvania in 1824, coming soon after 

 to New York city, where all his active profes- 

 sional life was spent. At this period he was 

 associated with his relative Charles Fenno Hoff- 

 man in the charge of the American Monthly, 

 and in 1835 published two works, viz., "Le- 

 gends of a Log Cabin," reminiscences of his 

 western life, and " Life on the Lakes," a series 

 of letters describing his journey to the Pictured 

 Rocks of Lake Superior, to which himself and 

 brother were the first white visitors for non- 

 mercantile purposes. 



. He was elected Professor of Obstetrics in the 

 College of Physicians and Surgeons of New 

 York, in 1841, and continued in this position 

 till his death, uniting with it, after the decease 

 of Dr. Beck, the Professorship of Medical Juris- 

 prudence. In this department he was soon 

 acknowledged as an expert, and on few cases 

 of interest was he not consulted by the ablest 

 members of the Bar. In many he appeared as 

 a prominent witness, and here his clearness of 

 conception, ready knowledge and fearlessness 

 of temperament, enabled him to sustain fully his 

 own dignity and that of his profession. In 

 private practice he endeared himself by his 

 sympathy with the sufferings and anxieties of 

 his patients, while he was much consulted by 

 his professional brethren, and performed many 

 important operations in obstetrics and surgical 

 midwifery, in which his scientific knowledge 

 and practical skill insured him a large measure 

 of success. In lecturing he made no pretence 

 to grace or elegance in measure and style. His 

 attitudes were careless, his language unstudied, 

 his sole aim was to instruct, but his lectures, 

 for practical utility and correct scientific teach- 

 ing, have never been surpassed. He had a taste 

 for Natural History, great fondness for micro- 

 scopic investigation; he spoke and read French 

 and German ; his classical knowledge was ex- 

 tensive and accurate; with the modern English 

 classics he was thoroughly familiar, and most 

 intimately acquainted with both Ancient and 

 Modern History. He possessed a retentive 

 memory, great aptitude of quotation, quickness 

 of repartee, keen perception of humor, and col- 

 loquial powers of the highest order. 



He prepared for the press Dr. Beck's "Lec- 

 tures on Materia Medica," took charge of the 

 two later editions of "Beck's Medical Juris- 

 prudence," wrote "A Sketch of the Life and 

 Character of Dr. J. B. Beck" in 1851; "The 

 Relations of the Medical to the Legal Profes- 

 sion" in 1856; a "Medico-Legal Examination 

 of the Case of Charles B. Huntington," trans- 

 lated from the German of Bischoff ; " Tracts on 

 Generation," with numerous contributions to 





medical magazines, and one to Appletons' t; Cy- 

 clopffidia." In May, 1864, failing health induced 

 Dr. Gilman to abandon the practice of his pro- 

 fession ; he removed to Middletown, Connecticut, 

 where he regained some degree of strength, but 

 disease of the heart suddenly terminated his 

 life on the evening of the 26th of September, 

 1865. 



GLASS. Certain new products in the way 

 of glass-making, as well as also certain prin- 

 ciples relative to the structure of glass, its du- 

 rability, etc., which have recently been noticed 

 in the scientific journals, are deserving of men- 

 tion in this place. 



Crystalline Nature of Glass. The surface 

 of glass etched by fluorhydric acid presents a 

 different appearance, according as the etching 

 is done with the acid in the gaseous or the 

 liquid form. Dr. C. M. Wetherill (Amer. Jour, 

 of Science, January, 1866) disproves the hither- 

 to accepted explanation of this difference, and 

 of the ground-glass appearance in the former 

 case to the effect, namely, that in etching 

 with the gaseous acid the products of decom- 

 position remain in the corroded cavities. He 

 states the result of examination with the micro- 

 scope to be, that the gaseous acid corrodes the 

 surface in minute and shallow cavities, in 

 which after cleansing with water no other sub- 

 stance than glass is found ; while the depres- 

 sions are deeper and more irregular as the ac- 

 tion has been more prolonged. The vapor 

 must, therefore, apply itself to the glass in mi- 

 nute drops or vesicles, like those formed with 

 moisture by antozone. The liquid acid, how- 

 ever, corrodes the whole surface with a certain 

 uniformity; and examination of such surface, 

 it is stated, reveals in every instance the crys- 

 talline nature of glass. The semi-opacity of the 

 glass etched by the gaseous acid appears due 

 solely to the influence of the irregularities of 

 surface on the rays of transmitted or reflected 

 light. 



Leydolt first announced (Wiener Acad. 

 JBericht, viii., 261) the discovery that glass is 

 to some extent crystalline. His examination 

 seemed to show that in all glass there is an 

 amorphous matrix interspersed in less or 

 greater degree with crystals ; and that the dis- 

 tribution of the latter, not less than the gen- 

 eral density and composition of the glass, has a 

 marked influence upon its character and optical 

 behavior. M. Daubrec, on the contrary, has 

 asserted that the crystals discovered on the 

 etched surface of glass are really deposited 

 crystals of fluo-silicide of potassium, which then 

 protect from corrosion the parts beneath them. 

 M. Pelouze denitrified various kinds of glass, 

 by exposing during 24 to 48 hours to incipient 

 fusion, and afterward cooling slowly : the glass 

 lost its transparency, turning to a porcelain- 

 like mass, which contained numerous opaque 

 acicular crystals. This product could be re- 

 fused into glass, then produced anew from the 

 latter; and so on, repeatedly. Later experi- 

 menters have, however, contradicted M. Pe- 



