182 Mr. A. Gages on Vivianite. 



This splitting of the jet also shows how great the influence of 

 the vibrations of the efBux-oriliee are upon the jet. 



Effect of a note upon jets issuing from angular openings. 



182. If we examine, by means of the rotating slit, a stream 

 which flows out of an angular opening from above downwards 

 during the existence of a note, we see that the higher portion, 

 which shows with gi'eat regularity the singular forms described in 

 the previous part of these investigations (§§ 44, 45, 61, 64), con- 

 sists of a continuous mass of water, and that where the regularity 

 is less, rounded masses are formed in the stream. At the com- 

 mencement of their formation these masses appear to be com- 

 posed of several spheres or drops, formed at the edges i r, i^ r^ of 

 the surfaces described in § 45, where these surfaces, even to the 

 naked eye, no longer appear smooth and continuous. These 

 spheres gradually unite to a single drop, which still at first 

 shows traces of its derivation, but continually assumes more and 

 more the spherical form. In fig. 24 the attempt is made to 

 represent this appearance as it is presented by a jet flowing 

 out of a long four-sided opening (§ 14), and seen through the 

 revolving slit. 



183. If a sounding body or the magnetic hammer (§ 125) be 

 applied to the vessel from which the stream flows, or to the 

 stand upon which the vessel is placed, no swellings, it is true, 

 are formed, as is the case with the circular orifice, but the forma- 

 tion of drops begins (in consequence of the vibrations) at a less 

 distance from the efflux-orifice, and at more uniform intervals 

 of time, than when no note is sounded. In streams of greater 

 diameter this action of the note is less noticeable, but in thinner 

 ones it is very distinct. The influence which the vibrations of the 

 efflux-orifice exercise upon jets which issue from angular orifices, 

 is therefore precisely similar to the effect when the orifices are 

 circular, although in the former case no swellings are formed. 



XXVIII. On Vivianite. By Alfhonse Gages, M.R.I. A."^- 



^r^IIE important functions which phosphates perform in 

 1- organic nature, give peculiar interest to everything con- 

 nected with the history of their occurrence as minerals. They 

 are found in all formations, not excepting igneous rocks; but 

 the crystallized phosphates are more usually found in the older, 

 while the nodules or masses of phosphate of lime chiefly occur 

 in the more modern formations. Vivianite is, however, a striking 



* Communicated liy the Author. 



