The bottle or can should be carefully labeled. The following form of label,1 used by the Bureau of Mines, should be placed on samples shipped to the bureau:

Department of the Interior

Bureau of Mines

Information to accompany each sample of fuel petroleum submitted for analysis

If refined to any degree, state name and location of refinery..

Condition of sample when received by Bureau of Mines.

The label should be carefully written with a hard lead pencil on a strong mailing tag, and this tag should be securely tied to the can. The lead pencil should be pressed firmly against the tag so as to indent its surface. An inscription thus written is legible even after the paper has been wet with oil. Gummed labels should not be used; they are easily detached if slightly moistened, and may be lost. A duplicate copy of the record on the label should be mailed to the engineer in charge, Bureau of Mines, Pittsburg, Pa.

SAMPLING CEMENT

The following recommendations are taken from the report of the Committee on Uniform Tests of Cement of the Am. Soc. of Civil Engineers as amended Jan., 1908.

"1. Selection of Sample.-The selection of the sample for testing is a detail that must be left to the discretion of the engineer; the number and the quantity to be taken from each package will depend largely on the importance of the work, the number of tests to be made and the facilities for making them.

"2. The sample shall be a fair average of the contents of the package; it is recommended that, where conditions permit, one barrel in every ten be sampled. 1 These labels will be furnished on request.

"3. All samples should be passed through a sieve having twenty meshes per linear inch, in order to break up lumps, and remove foreign material; this is also a very effective method for mixing them together in order to obtain an average. For determining the characteristics of a shipment of cement, the individual samples may be mixed and the average tested; where time will permit, however, it is recommended that they be tested separately.

"4. Cement in barrels should be sampled through a hole made in the centre of one of the staves, midway between the heads, or in the head, by means of an auger or a sampling iron similar to that used by sugar inspectors. If in bags, it should be taken from surface to centre."

A sampling iron is shown in Fig. 98; the point is an auger, enabling one to bore through the staves.

Inasmuch as a mixture of samples will not reveal irregularities in quality, it is best (except as noted above) to keep samples separate. Each sample should be dated and tagged

with the car number and initials, so that it can be positively identified with the shipment it represents.

The quantity of each sample will de

pend on the conditions given in clause FIG. 98.-Sampling iron for cement No. 1 above, but it will usually be about

testing.

8 or 10 lb. Mason (fruit) jars make good sample jars. (Richards and North "Manual of Cement Testing;" Van Nostrand, 1912.)

SAMPLING SAND FOR TESTING FOR USE IN CONCRETE

In the "Engineering News" for Feb. 5, 1914, p. 306, is an article entitled "The Testing of Sand for Use in Concrete, I. Field and Laboratory Practice" by Mr. Cloyd M. Chapman, in which is described the methods. in use by Messrs. Westinghouse Church Kerr & Co. Below is reproduced the portion of the article dealing with the method of taking the sample in the field. Mr. Chapman emphasizes the importance of care in this part of the work, showing that "the value of a test is entirely dependent upon the degree of accuracy with which the sample of sand represents that from which it was taken," and that "to test an improperly taken sample of sand is not alone a waste of the time and money involved in making the test but may lead to much greater loss if the results of the test are used in specifying proportions for large quantities of concrete."

While not stated directly in the text, it may be noted that the size of sample which is to be shipped to the laboratory is given on the "Sand Shipping Notice" as being 4 quarts.

Taking Sample in Field and Shipping. Container.-Air-tight cans having tight fitting covers or corks should be provided for shipping samples from the field to the laboratory. A wood covered or crated air-tight metal can makes a very satis

factory container, which can usually be used over and over again. Avoid shipping samples of sand in bags, in cigar boxes or other wood containers, as they allow the sand to dry out before being tested.

Sampling Before Shipment.-When it is practicable to keep an inspector at the sand bank at all times while shipments are being loaded, so that it may be positively known that the sand which is sampled is the sand which is shipped, then samples should be taken at the bank before loading. Or, if sand is obtained from a source which is known to produce no poor sand, has no spots or streaks of poor sand, has no overburden of loam or other objectionable material which might become mixed with the sand before it is shipped, and is in all respects a deposit from which a uniform grade of sand may be depended upon, then the samples may be taken at the bank without the maintenance of an inspector at the bank.

Taking Sample of Bank.-In sampling a bank of sand which has exposed vertical or steep sloping faces a small channel of uniform size is scooped out of the face from bottom to top. Fig. 1 (not reproduced; Auth.) shows a sample being taken in this manner. The sand scooped from this vertical channel, if more than enough to fill the container, is thoroughly mixed and reduced by quartering to the quantity desired. A tin dipper or can is a suitable tool with which to cut out the sample. By cutting such a groove or channel at each of the faces in the bank from which sand is obtained, samples are secured which represent with a fair degree of accuracy the sand in the bank. The samples taken from the various faces are not to be mixed together, but are marked for identification as to location and sent separately to the laboratory for examination.

If the bank contains both good and poor sand, and it is necessary to maintain an inspector at the bank to insure the shipment of good sand and to sample the sand to be shipped, then the samples may be taken from the piles or bins of sand being loaded.

Taking Sample from Piles at Bank.-Samples are taken with a small tin box such as a pepper or spice box, holding half a pint or less. With this small receptacle portions of sand are scooped up from many parts of the sand pile, filling the receptacle each time and emptying it into the larger can in which it is to be sent to the laboratory. The number of samples to be sent to the laboratory is very largely a matter of judgment on the part of the inspector. Whenever there is any doubt as to the quality of any shipment of sand, a separate sample should be taken of that shipment.

Taking Sample on the Job.-In sampling sand after its arrival on the job, the same general rules are to be followed. A small receptacle such as a glass tumbler or tin box holding not more than half a pint should be used, and the can which is to be sent to the laboratory is filled by taking sand from as many parts of the pile as is necessary to fill it. The sample should be taken from the inner part of the pile as the outer part and especially what rolls down the outside, may be composed largely of the coarser grains or pebbles.

Taking Samples after Delivery.-Samples should be taken from the shipments of sand as they arrive on the job. A preliminary inspection is to be made of the lot, whether wagon loads, carloads, barge loads, or other sort of shipment, to ascertain whether the sand appears to be all of a uniform quality and size. If the various units of the shipment seem to vary, a separate sample shall be taken of each unit and the units shall be kept separate until the sample has been examined

and reported upon by the laboratory. For instance, if two carloads of sand are received, one of which is evidently finer than the other, then a separate sample shall be taken of each car, and if it is necessary to unload the cars at once they shall not be unloaded onto the same pile but shall be kept separate, provided there is any doubt in the inspector's mind as to the suitability of either sand for the work in hand. The samples shall be taken if possible during the unloading, when the shipment is in cars or barges, or from the pile after the wagon has dumped when the sand is received in wagons.

Marking and Shipping the Sample.-To the can containing the sample is securely attached a shipping tag giving the name or number of the job from which the sample is shipped, the name of the dealer furnishing the sand, the quantity of sand in the shipment represented by the sample, the exact location of the bank or deposit from which the sand was shipped, and the signature of the inspector who took the sample.

The sample is then shipped by express to the laboratory for examination.

At the same time that the sample is shipped, all of the above information relative to the sample shall be sent by mail to the laboratory on the Sand Sample Shipping Notice, so that in case the tag on the can becomes defaced or torn off, the information required will still be available. Fig. 99 shows a facsimile of such a notice properly filled out.

FIG. 99. Facsimile of sand shipping notice, used in sand testing, Westinghouse Church Kerr & Co. (Actual size of card 3 × 5 in.)

General Cautions.-The sample must truly represent the average of the entire shipment, or that part of the shipment from which it is taken.

The sample must be put into the air-tight container as fast as it is taken from

the pile, so that it shall not have time to lose any of its moisture.

The container must be well corked or sealed before shipment to the laboratory.

COLLECTION OF SAMPLES OF WATER OR SEWAGE FOR ANALYSIS

The following directions are taken from the "Standard Methods for the Examination of Water and Sewage" published by the American Public Health Association.

Quantity of Water Required for Analysis.-The minimum quantity necessary for making the ordinary physical, chemical, and microscopical analysis of water or sewage is 2 liters (0.528 gal.); for the bacteriological examination, 2 oz. In special cases larger quantities may be required.

Bottles. The bottles for the collection of samples shall have glass stoppers except when physical or microscopical examinations only are to be made. Pottery jugs or metal containers shall not be used.

Sample bottles shall be carefully cleansed each time before using. This may be done by treating with sulphuric acid and potassium bichromate, or with alkaline permanganate, followed by a mixture of oxalic and sulphuric acids, and by thoroughly rinsing with water and draining.

When clean the stoppers and necks of the bottles shall be protected from dirt by tying cloth or thick paper over them.

For shipment bottles shall be packed in cases with a separate compartment for each bottle. Wooden boxes may be lined with indented fibre paper, felt, or some similar substance, or provided with spring corner strips, to prevent breakage. Lined wicker baskets also may be used.

Bottles for bacteriological samples, besides being washed, shall be sterilized with dry heat for 1 hour at 160° C., or in an autoclave at 120° C. for 15 minutes. For transportation they may be wrapped in sterilized cloth or paper, or the necks may be covered with tinfoil and the bottles put in tin boxes. When bacterial samples must of necessity stand for 12 hours before planting, bottles holding more than 4 oz. shall be used.

Time Interval between Collection and Analysis. Generally speaking, the shorter the time elapsing between the collection and the analysis of a sample, the more reliable will be the analytical results. Under many conditions, analysis made in the field are to be commended, as data so obtained are frequently preferable to those made in a distant laboratory after the composition of the water has changed en route.

The allowable time that may elapse between the collection of a sample and the beginning of its analysis cannot be stated definitely, as it depends upon the character of the sample, and upon other conditions, but the following may be considered as fairly reasonable maximum limits under ordinary conditions: