494 THE POPULAR SCIENCE MONTHLY. 



8. " On the Projection of the Spectra of the Metals" {American Journal of 

 Science for September, 1865). 



9. " On the Construction of a Spectroscope with a Number of Prisms by 

 which the Angle of Minimum Deviation for any Pay may be accurately 

 measured " {American Journal of Science for November, 1865). 



10. " On the Heat of Friction" ("Proceedings of the American Academy," 

 1865). 



11. "On the Aqueous Lines of the Solar Spectrum" ("Proceedings of the 

 American Academy," 1866). 



By comparing observations with the spectroscope and the hygrometer, it was 

 in this paper first shown that a large part of the air-lines in the solar spectrum 

 are due to aqueous vapor. 



12. " On Danalite, a New Mineral Species from the Granite of Rockport, 

 Massachusetts " {American Journal of Science for July, 1866). 



This is a well-marked species allied to Helvin, but containing zinc in place 

 of manganese. 



!- ' 



13. " On Cryophyllite, a New Mineral Species of the Mica Family, with Some 

 Associated Minerals in the Granite of Eockport, Massachusetts" {American 

 Journal of Science for March, 1867). 



Besides establishing a new species, this paper shows that in the veins of the 

 Rockport granite there are closely associated a unicilicate and a bisilicate mica, 

 which are isomorphous with each other, a circumstance which renders probable 

 the theory that the wide variations in the composition of the micas may result 

 from an isomorphous mixture of two similar types. 



14. " On Certain Lecture Experiments, and on a New Form of Endiometer " 

 {American Journal of Science for September, 1867). 



15. " A Method of determining the Amounts of Protoxide of Iron in Sili- 

 cates not soluble in the Ordinary Mineral Acids " {American Journal of Science 

 for November, 1867). 



16. " Crystallographic Determination of Some American Chlorites" {Ameri- 

 can Journal of Science for September, 1867). 



The paper gives some new measurements of angles, and shows that there 

 are two crystallographic types of chlorites corresponding to the well-known 

 types of micas. It is further shown that tbere is a variation of optical angles 

 in the chlorites, even on the same specimens, like that observed with the micas, 

 and the inference is drawn that the variation is due to a similar cause. 



17. "Atomic Ratios" {American Journal of Science for May, 1869). 



It was for the first time pointed out in this paper that what mineralogists 

 have long called the oxygen ratio of a silicate is really the ratio between the 

 atomicities of the acid and basic radicals in these salts. 



18. " The Vermiculites their Crystallographic and Cnemical Relations to the 

 Micas, together with a Discussion of the Cause of the Variation of the Optical 

 Angle in these Minerals " ("Proceedings of the American Academy," 1873). 



This monograph contains the chemical analyses and crystallographic descrip- 



