J a n . , 1917
T H E JOURNAL OF I N D G S T R I A L A N D ENGINEERING CHEMIST R Y
in winter. It contains only a few per cent of condensed water, I t seems as if in building filtration plants, in conjunction with pumping stations, some of t h e heat from exhaust steam could, either by t h e above method or some other, be used t o raise t h e temperat u r e of t h e water t o be filtered, even if only a few degrees. T h e striking advantage of warming t h e water supply is well known, but, of course, coal cannot be burnt solely t o heat t h e water. Where swimming pools are t o be supplied with water t h a t is originally of such low alkalinity as t o give practically no reaction with alum, i t is of course difficult t o devise a way t o fill them t h e first time. If t h e raw water supply could be first fed into a pair of capacious tanks a n d there treated with bicarbonate using alternate tanks, i t would solve t h e problem easily. This could be done except for t h e probability t h a t so much space could rarely be provided. IThere t h e city water supply is of sufficient purity a n d clearness t o be used without filtration for t h e first filling of t h e pool, this trouble is eliminated. Where alum a n d bicarbonate solutions can be fed into t h e running feed water b y gravity from tanks with regulating valves as is done in larger filtration plants, there would be no question a t all, b u t as far as t h e writer knows, swimming pools are usually supplied with alum-Eeeding devices and filters all under city water pressure. This works fairly well with waters of high enough alkalinity a n d also will be satisfactory for refiltering water from t h e swimming pool because t h e bicarbonate can be added t o t h e pool before refiltration. Such plants use potash alum in large crystals which are packed in a closed t a n k under water pressure a n d t h e water, i n slowly passing through t h e t a n k full of alum, becomes a saturated solution. T h e undissolved alum retains its massive condition on account of its relatively slight solubility. T h e t a n k therefore does not choke up. Sodium bicarbonate cannot be used in a n y such device because of its solubility a n d fineness. &4 solution of i t in such a pressure t a n k would be constantly changing in strength b y progressive dilution a n d any undissolved bicarbonate would pack tightly in t h e t a n k so as t o stop t h e flow. For t h e same reason aluminum sulfate cannot be used in such pressure-filtration systems. It is a strange fact t h a t makers of pressure filters will contract t o provide filtration plants for swimming pools in t h e face of t h e above difficulties a n d make n o provision whatever for supplying artificial alkalinity, They must know very well t h a t t h e alkalinity mill be exhausted after a definite number of refiltrations and t h a t raw water with low alkalinity will not react a t all. It is generally conceded among filter men t h a t one grain of aluminum sulfate per gallon of water is t h e minimum and t h a t each grain per gallon removes 7 parts carbonate per million. On this basis i t would require in t h e neighborhood of I O pounds of bicarbonate for each turn-over of a 70,000 gallon pool. JOHNSON
&
JOHNSON
LABORATORIES
NEWBRUNSWICK, NEWJERSEY.
57
SOME LABORATORY CONVENIENCES By A. E. PERKINS Received Xovember 27. 1916
Fig. I illustrates a flat bottomed Kjeldahl flask used t o replace t h e special flask described in connection with t h e writer's extraction apparatus.l I n these days when all kinds of hand-made and special glass apparatus is so expensive and so difficult t o obtain, t h e advent of a n y simple b u t efficient homemade substitute should be welcome. Fig. I is selfexplanatory. The coiled spring D may' be satisfactorily made from KO.2 0 brass spring wire. We make use of alundum extraction capsules, C, b u t there would seem to be no good reason why other forms could not be used equally well. We are also now making use oE t h e regular stock size test tube I O in. X I in.> for t h e condensers B instead of t h e special size specified in t h e original description referred t o above. Fig. I 1 illustrates a simple, convenient, and very satisfactory home-made burette support. T h e support is attached t o t h e overhead shelf E , on which t h e bottles l , , ,@ ,#
"
B
'
y
@
,
I
FIG.I1
of standard solutions are kept. This arrangement leaves t h e table t o p free from encumbrance. The novel feature of t h e support as here described may be briefly stated as follows: A , t h e rod t o which t h e burette clamps are attached, is of 3/8 in. diameter and may be of any convenient length. It is threaded for about 6 in. on t h e upper end. B , B are hardwood strips 18 in. X 2'/2 in. X '/B in. bored a t a suitable distance from t h e end t o permit the p a s a g e of the rod A . B is their vertical projection. A burr and washer are provided above and below each of the strips B . B , as shown a t A'. These when tightened hold the rod a n d strips securely in place. t h e distance between B , B , being adjusted according t o t h e thickness of t h e shelf. -4 slit or groove G, in. wide and as long as desired, is cut beginning near t h e other end of each of the strips B , B; a 3/s in. bolt of proper length is prorided with a washer; and a burr with attached lever, or t h u m b n u t as shown at C,D ,grips t h e support firmly to the shelf. T H I S JOURNAL. 6
(1913). 148.
T H E JOURNAL OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
58
T h e support is most rigid a n d substantial a n d can be quickly a n d easily adjusted to a n y desired position above t h e table. The Allihn, Lincoln, or Hoffman burette clamps, as listed b y dealers, are satisfactory for use with this support. T W O C O N V E N I E N T P I P E T T E S FOR SAMPLING MILK A N D
MILK PRODUCTS
The writer has h a d in use for some two years a special form of pipette as shown in Fig. 111, for t h e measurement of milk samples for chemical analysis. For most determinations a pipette is employed which is graduated on t h e stem in 0.01 cc. t o contain 9.6 t o 9.8 cc., making i t easy a n d practicable t o measure out samples of milk weighing exactly I O g., whatever t h e specific gravity of t h e milk. The specific gravity is always determined in advance and t h e volume of t h e sample taken is governed accordingly. I n use t h e pipette is filled t o t h e desired point, t h e milk is allowed
a
a
A
NOVEL
AND
C O N V E N I E N T DRYING
Vol. 9 , No. RACK
I
FOR
LABORATORY G L A S S W A R E
The frame of this drying rack a, a (Fig. I V ) , which is made of wood t o match t h e interior woodwork of t h e laboratory, is in t h e form of a wall case with open front, and may be made of any convenient dimensions. A vertical transverse section is given, showing the arrangement of t h e shelves. T h e exact dimensions a n d spacings must again be left to t h e judgment of t h e user. The back of t h e case is covered with galvanized sheet iron as shown a t b , b ; t h e shelves s, s, also made of t h e same material, are supported a t t h e ends by wooden cleats, and slope toward t h e back. A small space is left between t h e shelves a n d t h e back of t h e case. A double hem about t o I in. wide is turned upward at right angles t o t h e surface of the shelf along its front edge, and a similar hem y is turned downward at t h e back edge; these serve t o make t h e galvanized iron shelves rigid. A piece of galvanized wire cloth resting on t h e t o p of this hem, a n d on t h e back of t h e shelf, as shown b y C, forms t h e surface on which t h e beakers, dishes, funnels, etc., are inverted after washing. T h e drip from these dishes runs t o t h e galvanized iron shelf, t o t h e back of t h e case and thence to a shallow metal tray, T , a t t h e bottom of t h e case. This t r a y is inclined towards one corner where a connection t o t h e drain is provided as shown at d. No drip from t h e dishes on one shelf reaches t h e dishes on t h e shelf beneath. Moreover, this arrangement is very economical of space, which is so often at a premium about the laboratory sink, and t h e dishes, particularly beakers, drain much better t h a n when they are inverted on a level surface. OHIO
DAIRY CHEMICAL LABORATORY AGRICULTURAL EXPERIMENT STATION WOOSTZR, OHIO
HANDLING A STANDARD SOLUTION OF BARTUM HYDRATE B y W.G.HAYNE5 Received November 9, 1916
FIG.I11
FIQ. IV
to r u n out, a n d t h e pipette is then rinsed with water. Before measuring t h e next sample the water is rinsed from t h e pipette with a portion of t h e milk which is being sampled. T h e use of samples weighing exactly I O g. very greatly facilitates t h e work of calculating results. A pipette of t h e same general nature graduated on t h e stem in 0.1cc. from 63 t o 65 cc., as also shown in Fig. 111,proves a great convenience in measuring samples of milk or milk products, for t h e determination of lactose b y a polariscope provided with t h e Ventzke sugar scale, These pipettes were most carefully a n d accurately made for the writer by Louis F. Nafis, Scientific Glassware Manufacturer of Chicago, Ill.
I n handling a standard solution of barium hydrate here in t h e laboratory of t h e Union Pacific R. R. Co., considerable annoyance was caused b y t h e usual arrangement of having a siphon tube leading f r o m t h e supply bottle t o the bottom of t h e burette, a n d attached t o the same b y a piece of rubber tubing, and closed by means of a pinchcock. The constant cracking and consequent leaking of t h e tubing a t t h e pinchcock was so troublesome t h a t t h e following piece of apparatus was substituted with much success. As i t is original so far as is known, t h e writer thought it would be a good idea t o publish it. The only materials needed are: a small “T” tube, a piece of glass rod about 8 in. long, a small piece of wire about t h e same length, one small rubber stopper, a n d 3 in, of small, heavy-walled rubber tubing, a flame, a n d about one hour’s time. Referring t o t h e accompanying sketch, t h e apparatus is made as follows: first, close t h e end of t h e T - t u b e a t B b y heating in the flame, leaving t h e opening E
