AN IMPROVED INTERSTITIAL WATER SAMPLER 1

NOTES AND COMhlENT even though a certain irreducible flotation area would be necessary to prevent over- turn in cross seas. For larger instrument loads, larger tubes could be used. Theoretical calculations of the response of an articulated float do not appear to be available although Peters (1950) has treated an allied problem. Floats can be fabricated cheaply, so a few trial installations should give suitable ranges of design criteria. Early thought was given to the use of a specially fabricated rubber mattress. (It would be articulated only broadside to the sea.) This might be preferable to the pres- ent design, but fabrication of a prototype promised to be prohibitively expensive in this case. AN IMPROVED A grant to D. V. Anderson from the Ca- nadian National Research Council helped finance this project. D. V. ANDERSON Department of Mathematics, University of Toronto, Toronto, Ontario. D. H. MATHESON Municipal Laboratories, City of Hamilton, Ontario. FUZFERENCES PETERS, A. S. 1950. on water waves. MARINE TECH. Sot. Trans. Buoy Tech. Washington, D.C. INTERSTITIAL Modifications of filter presses have been used for some time by workers in the pe- troleum field for extraction of interstitial water from drilling muds. They have been used on sediments by Lusczynski ( 1961) and Hartmann ( 1965), who used commer- cially available pistonless presses, and by Siever ( 1962), who used a specially de- signed piston-type press or squeezer. This note describes an inexpensive nonmetallic squeezer suitable for trace metal studies. Several of these squeezers may be operated simultaneously using a simple manifold. This squeezer is gas-operated and has no piston or moving parts. Gas pressure acting against a rubber diaphragm compresses the sediment and forces interstitial water through filters into a sample bottle. Delrin and nylon are used throughout, resulting in a noncorrodible and easily cleaned squeezer. Pressures up to 200 psi (14 bar) may be used for squeezing and leaks that occur during operation are easily stopped by fur- ther compressing the O-ring seals with the l Contribution No. 100 from the Chesapeake Bay Institute and the Department of Oceanography, The Johns Hopkins University. This work was supported by U.S. Atomic Energy Commission Contract AT ( 30-l ) 3497. WATER The effect of a floating mat Commun. Pure Appl. Math., Buoy technology. Symp., 24-25 March 1964, 504 p. SAMPLER' C-clamp squeezer holder. The absence of a filter plate and a drip space minimizes evaporation and gas exchange which usu- ally result from foaming. This squeezer may be operated in any position and may be used for samples of different sizes by varying the length of the retainer section. The cost is about $50.00. An exploded view of the apparatus is shown in Fig. 1. Fig. 2 shows the assem- bled squeezer. Several squeezers have been operated from the same gas source using an inter- mediate pressure regulator to supply gas to a manifold consisting of shutoff valves for controlling the gas supply to each squeezer and a needle valve for releasing internal pressure before disassembly. Flex- ible nylon pressure-tubing [%-inch (4.75 mm) OD, 2,500 psi ( 172 bar ) burst pressure] and Swagelok (Crawford Fitting Company, Solon, Ohio) fittings with nylon ferrules were used for all tubing connections. Hel- ium, carbon dioxide, and nitrogen have been used as the squeezing gas. Several discs of Nitex nylon screen placed in the filter well provide lateral permeability and filter support. Membrane filters have been used with the nylon screens and several