I I44
T H E J O U R N A L OF I-VDUSTRIAL A N D ENGINEERING CHEMISTRY
current is accordingly flon-ing only part of t h e time when the thermostat i s used under these conditions. T h e cabinet may be employed for other lines of investigation a t higher temperatures, which would be Upper She/f I
bL
0wer She4
r
Tol. 8, S o .
z2
thus arranged does not r a r y more t h a n 0 . 5 ' C if properly adjusted. The heat-regulating system may be rendered niore efficient b y having a variable external resistance or rheostat in series with t h e heating elements. While not essential, this can be employed t o reduce the number of makes and breaks occurring in t h e thermoregulator. A little experience with a thermostat enables one t o judge of the proper additional resistance t o insert b y means of the rheostat when the surrounding air temperature is known. .4 rheostat of this kind can be purchased for about $8.00, while a satisfactory one may be constructed b y anyone with mechanical ingenuity for $4.00 or even less. The cost of t h e completed thermostat IS shown below. T h e cabinet in this laboratory was built of clear cypress, although white pine could possibly be used a t a slightly reduced price. Tt was finished inside and outside with white enamel paint. T h e figures represent only t h e price of the materials. A rheostat is not included, as this is a non-essential though desirable accessory. T h e cost of winding and installing t h e heating elements is omitted as this would vary with the efficiency of t h e person employed. About 4 hours were required t o wind and install t h e coils and make the electrical connections described in this paper. COST OF COMPLCTED THERMOSTAT Cabinet ............................................ $40.00 1.25 lbs. No. 20 advance resistance wire.. . . . . . . . . . . . . . . 1.88 Thermoregulator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.00 Circuit breaker or relay.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.50 2 16-c. p . carbon lamps. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.30 0.75 1 15-ampere knife switch with fuses.. . . . . . . . . . . . . . . . . . . 25 feet No. 14 insulated copper wire.. . . . . . . . . . . . . . . . . . 0.25 3 doz. split porcelain knobs.. . . . . . . . . . . . . . . . . . . . . . . . . . 0.75 TOTAL
.........................................
$59.43
T h e writer does not claim t h a t t h e features of this cabinet possess a n y marked originality. The ideas expressed in its construction were gained from several sources. The device as finally assembled possesses a serviceability t h a t is outstanding, however. I t gives added value t o tests conducted by empirical methods, as a n y fermentation or baking test must be. No laboratory concerned with such work can long afford t o be without a uniformly heated, automatically controlled device of this character which can be obtained a t such a reasonable cost. CEREALA N D FLOUR LABORATORY DIVISIONO F -4GRICULTURAL CREMISTRY MIKKESOTA AGRICULTURAL EXPERIMCUT STATION
I' Cab,n e t
through carbon contacts in t h e relay. These contacts are moved in one direction by a spring, and in the other b y t h e electromagnets. The general scheme of the wiring system is shown in Fig. TT. The thermostat 1 Since writing this paper the No. 5 thermoregulator with condenser manufactured b y t h e Chicago Surgical and Electrical Company has been tested and found satisfactory for use in this thermostat. I t costs $10.00, a n d since no relay a n d carbon lamps are required when i t is employed, t h e cost of t h e complete thermostat is reduced b y $5.80. T h e wiring system is also simplified.
NOTE ON THE RESULTS OF ANALYSES ON FERTILIZER SAMPLES TAKEN WITH DIFFERENT STYLES OF SAMPLERS' By F. B. CARPENTER Received October 20, 1916
Having noticed the low results in ammonia on samples of fertilizer taken with the ordinary half round sampling tube, on goods which we had every reason t o believe contained t h e guaranteed percentage of ammonia, an experiment was made t o determine t h e 1 Presented a t the 53rd Meeting of the American Chemical Society, New York City, September 2 5 t o 30, 1916
Dec., 1916
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
relative efficiency of different types of samplers. For this purpose two bags of fertilizer were carefully made at one of our factories containing 7 . 2 0 per cent ammonia or a guaranteed percentage of 7 per cent. P a r t of t h e nitrogen was derived from nitrate of soda and t h e remainder from organic ammoniates. This fertilizer was sampled b y three different persons a t different times with three different types of samplers and t h e samples analyzed. The results of t h e analyses were as follows: SAMPLED BY Assistant Manager. Chemist ...................... Superintendent
Per cedt Ammonia No. 1 No. 2 No. 3
. . . . . . . . . . . . 6.48 6.90 ................ 6.43
Average
......................
6.67
6.90 7.21 7.17 7.09
.... ....
6.27
6.27
The results under No. I are from samples taken with old style half round tube; No. 2 new style round sampler, which opens and closes; No. 3 what is known as a rice sampler. The first result under No. z is lower t h a n t h e others for reason t h a t t h e sample was not properly manipulated; t h e tube was inserted into t h e fertilizer without being closed. The proper way t o handle t h e sampler is t o push t h e closed tube into t h e fertilizer t h e full length of t h e bag, open, t u r n u n t i l filled, close a n d withdraw. T h e results of these different analyses show t h a t t h e sampler which closes gives results on ammonia nearest t o theory, while with t h e other types t h e results are very much too low. As many of t h e agricultural departments still use t h e old style sampler, it is more t h a n probable t h a t many of t h e deficient analyses on samples taken b y official inspectors are a result of using improper sampling devices. This is a very important matter from t h e manufacturers’ standpoint and, while there has been no intentipnal neglect on t h e part of t h e fertilizer controls, i t is t o be hoped t h a t they will make a thorough investigation of t h e whole system of sampling a n d make such changes in existing methods as may be found necessary. VIRGINIA-CAROLINA CHEMICAL COMPANY RICHMOND, VIRGINIA
BETTER SAMPLES FROM THE FERTILIZER FACTORY1 B y A. J. LAWRENCE Received October 20, 1916
A great many useless analyses are made through lack of cooperation between t h e laboratory and the factory and even where there is a strong desire on the part of t h e superintendent t o have representative samples sent t o t h e chemist, trouble often arises through incorrect methods of sampling. I n t h e fertilizer industry t h e methods of collecting samples vary t o some extent in nearly every plant and we believe t h a t by standardizing these methods, much trouble could be eliminated and more accurate a n d reliable information would result. I n receiving raw materials, some contracts specify as t o t h e number of bags to be sampled. The large majority of sellers, however, leave t h e actual method 1 Presented at 53rd Meeting of the American Chemical Society, New York City, September 25-30, 1916.
1 I45
of sampling t o t h e sworn weigher. We have found considerable variance in t h e methods used by different weighers, many of whom do not realize t h e importance of their work a n d t h e trouble t h a t may arise between buyer and seller owing t o disagreement in analysis. An example of this is shown in a case in which there was considerable difference between t h e buyer’s and t h e seller’s chemists on a cargo of garbage tankage. The source of trouble lay in t h e fact t h a t t h e sworn weigher, without consulting t h e chemist or sampleboy, had quartered t h e fluffy, dusty material during a very high wind, in which a large amount of t h e fine particles were blown away, and in leaving, told t h e sample-boy t h a t he had gotten his sample and t h e remainder was in the barrel. The boy got his sample, not mentioning t h e incident, t h e results of which he did not realize. Also, a t times, where t h e samples are carefully mixed and quartered and t h e duplicates and triplicates agree excellently, still, lack of judgment in quartering on moist or dirty floors, or using brooms or shovels which are contaminated with foreign materials, will result in t h e analysis of t h e goods differing t o some extent from t h a t actually received. A considerable loss of money can very easily result through using t h e “bought” analysis on a lot of goods, which analysis may be slightly different from t h a t in the pile. I n one instance, a low-grade tankage was sampled, t h e sworn weigher requiring t h e unloaders t o take a handful from each cart and drop same into a burlap bag tacked t o t h e side of t h e scales. A large tin bucket was put on t h e other side of t h e scale house, a n d t h e men were required carefully t o take a cupful of sample from each cart and place same in t h e bucket. This experiment was tried because i t was believed t h a t in dropping t h e tankage into t h e bag, some of t h e fine ammoniated particles were lost b y being blown away from t h e mouth of t h e same; also it was noticed t h a t a considerable portion sifted through as each handful was thrown in. On several occasions t h e sample in t h e tin bucket showed a higher analysis, running from 2 j t o go cents per ton in valuation above t h a t obtained on t h e sworn weigher’s sample. The observance of these points would save considerable trouble later on should analysis be made in the piles and found t o disagree with the “bought” test. I n batching stock brands which are to be shipped after being cured, we do not believe t h a t enough stress is laid on t h e method of sampling. In t h e majority of plants, t h e usual plan is for t h e superintendent t o run up several tons of a brand and either have a sample drawn from t h e mill or t h e carts as they dump into t h e pile, or have t h e sample-boy dig down a few inches into t h e pile at several places. I n most instances, with careful sampling, fairly reliable results can be obtained in this way. However, from several experiments we find t h a t quite often very bad analyses result from this method of sampling and cause numerous retests in t h e laboratory as well as new samples from t h e pile. We believe t h a t this trouble can be eliminated t o a large extent by using a large prospecting auger
