NOTE 1. When AgNO, is used as the group reagent the procedure is unchanged except that HNO, must be detected in Group I. Interfering acids are nitrous, chloric, ferro and ferricyanic, sulphocyanic and the halogen acids.

Group V.

This group contains Arsenious, Chloric and Nitric acids which are not precipitated in the preceding groups, being soluble.

1. CIO. To a minor portion of the filtrate from the last group, add a piece of zinc, a few drops of HNO, and gently warm. A white curdy precipitate of AgCl shows the presence of chloric acid. Or to a portion of the filtrate add a little formalin, a few drops of HNO, and heat, a white curdy precipitate shows the presence of HCIO,. In both these tests there must be present an excess of the silver salt.

Remove the silver from the main portion of the filtrate from Group IV by adding a solution of NaCl as long as a precipitate forms. Filter, wash, reject the precipitate and test the filtrate as follows:

2. As2O. Acidify the filtrate with acetic acid and saturate it with H.S. If a yellow precipitate forms at once, arsenious acid is present. Filter, wash, and treat the filtrate under 3. (Omit test if arsenic was found in the analysis of the metals.)

3. Concentrate the filtrate to a convenient volume to expel H2S and in case chloric acid is present apply the "brown ring" test directly. Add an equal volume of conc. H2SO, to the test so that the two liquids will not mix, cool and pour down the side of the tube some FeSO, solution. Let the test stand for some minutes undisturbed. The formation of a brown or dark brown ring at the juncture of the acid and the test solution, shows the presence of nitric acid. Nitrous acid gives the "ring" with acetic acid in place of the H2SO..

4. To detect HNO, in the presence of HCIO,, acidify the concentrated filtrate, or a portion of it from 3 with acetic acid, boil for a minute with an excess of H2SO. Filter if uecessary, reject any precipitate and to a portion of the clear liquid add a drop or two of diphenylamine in conc. H2SO.. If a blue color appears at once, HNO, is present. This color slowly disappears.

This test depends upon the action of the sulphurous acid in changing any chlorate present into a chloride. To determine whether all the chlorate has been changed, add to the remaining portion of the solution a drop or two of aniline and then a few drops of conc. H2SO,. A blue color appears at once if any chlorate is present in which case use more of the H2SO. The appearance of a blue color with this test serves to detect a chlorate in the presence of a nitrate. The aniline test gives with a nitrate a yellow brown color.

5. BO1. To another portion of the filtrate apply the test for boric acid given under Group II, A, 1.

THOUGHTS ON THE PRACTICAL USE OF THE

METRIC SYSTEM.

By F. W. TURNER.

Mechanic Arts High School, Boston.

There have been many discussions of the advantages of the metric system of weights and measures by people who are very evidently in favor of the same, and, in most cases, they are men with considerable scientific or academic training. There have also been discussions, (sometimes) in opposition, by business men who are eminently practical in commercial pursuits, but who evidently do not take a very broad view of the situation. It would seem as though the subject might be profitably discussed by one who has had enough work in manufacturing to enable him to see the apparent difficulties on the practical side, and who, at the same time, is sufficiently in touch with academic work to enable him to appreciate the obvious advantages from the scientific aspect. From this introduction, it will be properly inferred that the writer is heartily in favor of the metric system and its introduction into this country, but also that we must recognize there are some objections which, while valid, are not insurmountable.

Comparing the present social condition with that of one hundred, or even fifty years ago, one cannot avoid noticing that the world, as far as communication is concerned, is growing very much smaller. People of different nationalities are becoming better acquainted, and various means have contributed to bring about this result. Civilization has increased and extended to many lands, transportation of intelligence as well as of material objects has been made swifter, surer and cheaper, and especial emphasis should be laid on the general prosperity which results in travel, thereby bringing about the mingling of different races. Many large enterprises are becoming international in character, and have correspondents and agents in many countries; but they are badly handicapped by the difference in language and customs.

Increasing intelligence has resulted in a gradual enlarging of the powers of the human mind so that the adoption of different units has become necessary. As examples, in this country, the science of gunnery has developed until 1000 yards is the unit of range, excavations are made on the basis of 1000 cubic yards, and the duty of pumping engines is expressed in foot-pounds

developed for 1,000,000 heat units supplied. While many units. have grown larger, on the other hand, the refinements in manufacture have grown closer to such an extent that even the most rabid opponent of the metric system has found it necessary to adopt .001 of an inch as a definite unit. Even this unit is being subdivided, and, in shop parlance, is called a "half thousandth" or "quarter thousandth." (Attention is called to .I of a millimeter as a far better standard.) Where units have changed, it is worthy of note that such changes are always decimal. If decimalization is desirable, why would it not be advisable to adopt a system which is purely decimal?

The introduction and adoption of new systems is inevitable to meet the broadening conditions which are constantly arising. The necessity of universal means of communication is shown in the general tendency toward decimalization not only of the English system but of all systems. The number of firms in this country using the metric system is constantly increasing, and the demand for measuring tools made to metric units has increased to such an extent that manufacturers now furnish them, not only in combination with English units, but also as purely metric instruments.

While systems of weights and measures are of great importance, there are other systems which will have to be considered before we can arrive at universal means of communication. Among them may be mentioned as of the first importance, the difference in language, which is intended to be met by the adoption, for international purposes, of Esperanto. The Christian Endeavor Society has recently adopted this language as its official means of communication, and it would seem that all societies having international connections might use it to good advantage. In the measurement of heat, it is to be hoped that the centigrade thermometer will displace all other makes, principally because it is so closely allied to the metric system. As a last word on this subject, is it too much to expect that some day we may have an international system of money values, possibly represented by about three units, not in the form of coin, but negotiable paper, the value to be fixed by delegates from all civilized countries?

Among the objections to the use of the metric system, and by these are meant really valid objections, may be mentioned the cost of changing tools and the trouble which would be inevitable

in making repairs, and in furnishing spare parts. It is possible to use both English and metric systems in the same shop. It has been done in some cases without confusion; one line of goods being manufactured under one system, and others under another system. The antagonism of the workman, which is often mentioned as one of the principal difficulties, is not so much antagonism as it is ignorance, and in nearly every case, the workman could use metric as well as English units if he would but think so. In one case which has come within the writer's knowledge, the superintendent on hiring workmen to work under this system, furnished measuring tools for the use of the workmen, told them it was a new kind of an inch, and he says that he never had the least trouble with any man on account of it.

The principal difficulty seems to be the conservatism of the people. This was not recognized until we began to develop an export trade, but now we find that our manufacturers are not willing to abide by foreign customs in regard to packing, billing, or in the matter of credit. This conservatism accounts in a large measure for the fact that they are not willing to use the system of weights and measures of the people they are trying to please. Our import trade, being so much smaller than our export, has not given us very much trouble, but a new industry has arisen which calls for fairly large imports, and it is found that the owners of foreign automobiles, all of which are made by the metric system, have great difficulty in obtaining in this country repairs or spare parts of any kind. This is particularly true in the matter of screw-threads and accompanying parts.

There are a few who honestly prefer the English system, and think that it is better than the metric system, simply comparing them as systems, and giving no attention to the troubles arising from change. There is also an honest difference of opinion regarding the desirability of a change in this country, and, of course, it must be recognized that no change can be made immediately or absolutely. The people must be educated, first, to understand the system, and, second, to use it in preference to the English system. One of the great difficulties in regard to its introduction is the fact that people are not sufficiently acquainted with it to avoid the necessity of translating everything back and forth from one system to the other. When people become sufficiently familiar with any system or any language, so they can

think in that system or language, nearly all the difficulties attending its use at once disappear. Of course the schools must be depended upon to teach the principles of the metric system to everyone, and it should be given more prominence in the lower grades than it has at present. In secondary schools we are now using the metric system entirely in physics and chemistry, but these do not seem to impress the people as being other than purely scientific attainments. In other words, people in general do not look upon physics and chemistry as being practical, and think that, being unpractical, they necessarily use unpractical units. In the schools where manual training is taught, it would be of immense advantage if the work in the laboratories, whether wood turning, forging, or machine tool work, could be done under a system of drawings, which should use metric units only. In the drawing room the metric system could be used to the entire exclusion of the English system. If anyone should argue that this would deprive a pupil of training in the system, which he would, in all probability, be obliged to use for some years to come, it may be answered that he would get sufficient training in the use of the English system in every-day life. In fact, he could not avoid it, and, as the object of the schools is to instill principles rather than particular systems, the student would be fitted to use English units if it should be desirable to do so. The large number of young men graduating from our higher technical schools, and each year entering the engineering field, are all so well grounded in this system that they will no doubt prove a potent factor toward its final adoption. If the system is to be thoroughly understood by the people, it must be taught, to the exclusion of other systems, by all the schools from the lowest to the highest.

The Idaho school for mines at Moscow, south of Spokane, has installed an assay laboratory at the state university, the building being 60 by 100 feet. The furnace room, 50 by 70 feet, contains 12 double muffle furnaces and several gasoline smelting furnaces. The metallurgical laboratory, a separate building, has a ground floor plan of 84 by 96 feet, being floored as in a mine mill. The equipment includes jigs, a stamp mill, cyanide and concentrating plants and other technical apparatus. The chemical laboratory is also complete and thoroughly modern.