NEWS

IN some articles inserted in this journal the author stated that pure steel, nearly free from phosphorus and sulphur and containing 25 to 30 per cent of carbon, stands easily the process of welding, if, indeed, the work is done with care and by clever workmen.

It may be mentioned here that to a steel ship-plate, 2 ft. wide and inch thick, a steel plate (2' x 2' x 3") was easily welded, and a perfectly clean and good joint was received.

In another case steel strips (6" x 4" x 1") containing 25 to 26 per cent of carbon were welded together; very often after cooling the plate was bent double, through the weld, without the least fracture in or near the welded part. In some experiments such plates were bent at a dark heat, and they often, not always, resisted this severe test, as it is known that at this temperature the steel is more liable to break. These trials show that Russian Bessemer steel is of a very good quality.

TENACITY OF STARCH.

By GEORGE WHEWELL, F.I.C., F.C.S.

IN consequence of the large quantity of farina (potato starch) which is used for the sizing and stiffening of yarn and cloth, the question often arises-Given several samples

of starch, which will make the stiffest cloth and which has the greatest tenacity? To my mind the best method devised so far is the one used by Shier, and is as follows:24 grains of the sample of starch are mixed with 400 grains of distilled water, and boiled with constant stirring for three minutes, then poured into conical test-glasses and allowed to stand for two hours; at the end of which time a flat metal disk seven-tenths of an inch in diameter, and not weighing less than 50 grains, is placed on the jelly and weights added until the skin is broken and the disk sinks.

In working the above method I find a difficulty in manipulating the weights on account of the smallness of the disk. If after a 50 or 100-grain weight has been placed on the disk you attempt to place a few smaller ones on also, the pressure is exerted unevenly, and the jelly is cut by the edge of the disk and not broken uniformly. I have devised the following modification, which I have used for the last three years, and find it to answer very well. The principle is to ascertain the number of grains required of any sample of starch which, when made into a jelly, will support a 100-grain weight for five minutes without breaking the skin. I have examined a large number of samples of farina, and find the number of grains required is from 18 to 28.

To determine the tenacity of a sample of farina I take, say, six conical shaped test-glasses 1 ounce capacity, and label the feet 18, 20, 22, 24, 26, and 28. Using a 2-ounce evaporating dish, I weigh out 18 grains of the farina, mix it with 26 c.c. of distilled water, and boil with constant stirring for three minutes. Pour it into the test-glass marked 18, and shake to make the surface of the jelly level, book the time, and allow to cool for exactly two hours. At the end of this time I take a 100-grain weight (mine being thirteen-twentieths of an inch in diameter), and place it on the jelly. If it is supported for more than

NOTE ON CHLORIDE OF CALCIUM.

By O. GLUGE, Sarrebruk.

THE manufacture of soda by the ammonia process has, during the last few years, been much developed, owing to the advances made by Mr. E. Solvay, and is likely to become more generally employed. It is possible that it may ultimately supersede Leblanc's method, as improvements are being constantly introduced into it.

The reaction which occurs in this manufacture, as all your readers are aware, takes place between bicarbonate of ammonia and chloride of sodium. Bicarbonate of soda is precipitated and hydrochlorate of ammonia remains in solution. The bicarbonate is separated by filtration, and the solution is employed to furnish fresh bicarbonate of ammonia. This is done by distilling the solution with lime; then ammonia is disengaged and a strong ley of chloride of calcium is left in the distilling apparatus.

I am anxious to direct the attention of your readers to this latter product, which is formed in considerable quantity and which is commonly thrown away as useless, as it has hardly been employed hitherto in manufacturing processes.

It would be very desirable that men of science and manufacturers should endeavour to ascertain if a more

extended use could be made of a product which can be got at such a cheap rate. The manufactures of soda by calcium in quantity, in solution, in crystals, or even in the the process above mentioned can furnish chloride of fused state to diminish the cost of carriage.

IN the CHEMICAL NEWS (vol. xxxviii., p. 300) I notice an excellent article "On the Determination of Specific Gravities." The author's points are well taken in reference to the importance of some uniform method either of performing the operation or of confuting results, and his suggestions could with great propriety be referred to some committee of one of the Societies for a report and recommendations that might be generally adopted.

Having occasion some years ago to take the specific gravity of some small quantities of distillates from petroleum products, I was led to adopt the following method, which was found to be entirely successful with so small a quantity as 3 cubic centimetres.

I prepared a cube of aluminium, which was intended to be of I c.c., but was accidentally obtained smaller. This was suspended by a platinum wire of the smallest size, and weighing only a few milligrms. The wire was first weighed, and then attached to the cube, which was then weighed in air, and then weighed just immersed in distilled water, and then in the oil. The difference between the weight in the air and in water gave the weight of the water; the difference between the weight in air and in oil gave the weight of the oil. The weight of the oil divided by that of the water gave the specific gravity of the oil.

This method admits of perfect control of the volume of

the liquids compared, and of just as perfect control of the temperatures as any other method. Moreover, it admits of very rapid execution and of operating on very small quantities of liquid. For taking the specific gravity of all ordinary oils and other non-corrosive liquids a cube of aluminium would be superior to a cube of platinum, on account of its lower specific gravity, and its permanence in the air renders it superior to any other of the so-called base metals.

For the class of liquids named I have found the results obtained by this method more satisfactory than those obtained by the bottle when the quantity available was unlimited; I therefore recommend the method without hesitation as applicable to very small quantities of liquid, as reliable, and as incomparably more rapid of execution than any other method with which I am acquainted.

It has often been my custom when ascertaining specific gravities for purposes of comparison to cool the oils to zero Centigrade. This temperature is very easily obtained by immersing the vessel in fragments of ice placed in a funnel from which the melted ice-water can readily flow away. It may not be generally known that water in which pieces of melting ice are floating will rarely cool a vessel to zero, usually not below two degrees. If a tripod holding the funnel is placed over the balance-pan, and a funnel is selected with a long neck bent nearly at a right angle, the water from the melting ice may be discharged into a beaker to one side, while the vessel, holding only a few c.c. of liquid is cooled completely to zero with the least possible trouble.

For purposes of comparison this arrangement furnishes results often of great value in technical operations in which rapidity of execution is often of more importance than that fastidious regard for accuracy which cannot be over estimated in questions relating to the absolute "constants of nature."

Chemical Laboratory, University of Minnesota,
January 31, 1879.

{CHEMICAL NEWS,

worked on this occasion ceased to indicate with sulphuric acid when more dilute than 1 to 50,000. The new indicator, on the other hand, remained sensitive to 1 part of sulphuric acid in 100,000 of water.

The solution of the indicator which I employ is made by dissolving I centigramme in 100 c.c. of distilled water, and contains therefore I part in 10 000. Even at this great dilution the liquid is of a full orange colour. It is worthy of remark that I centigramme of the substance is sufficient for five hundred determinations of acid or alkali; its cost is consequently inappreciable. It has also the advantage over litmus that its solution is less liable to decomposition on keeping.

The quantity of the solution of the indicator, of the strength given above, to be used in each determination is from one to two-tenths of a cubic centimetre. When this small quantity is added to a solution containing an alkali to be tested, there is no perceptible colouration as long as it is alkaline; but the faintest trace of acid turns the solution a pale but distinct pink tint, which is easily seen if the beaker be placed upon a sheet of white paper. The best way of applying the test is, after each addition of acid from the burette, to allow a drop of the indicator to fall on the surface of the liquid in the beaker after the contents have been well stirred. By this mode of proceeding the indicator is distributed over a smaller space, and the reaction is therefore more distinct.

An immense advantage which this indicator possesses over litmus is that it is entirely unaffected by carbonic acid; the solution need not therefore be boiled, and the operation consequently takes much less time; in fact, four operations can be made in the same time as one with litmus. That without boiling the solution it competes perfectly with litmus as regards accuracy may be judged from the following table:

Determination of Carbonate of Sodium Volumetrically. One c.c. of the standard sulphuric acid = 0·051176 grm. of carbonate of sodium. Carbonate of Sodium taken.

Grms.

0.6739

Standard Sulph. Percentage of Acid used. Carb. Sodium Cub. centims. obtained.

Indicator used.

Litmus.

Orange 3.

In order to determine whether the new indicator gave sodium, the following experiments were made upon a as accurate results with ammonia as with carbonate of solution diluted to 5 per cent for titration:

=

Determination of Ammonia Volumetrically. One c.c. of the standard hydrochloric acid grms. of ammonia. Ammonia taken.

Lunge has shown that, under certain circumstances tropæolin and "orange 3 are superior to litmus, as they are unaffected by carbonic acid and sulphuretted hydrogen; they are therefore especially valuable in the analysis of soda residues.

As this matter possesses considerable interest and importance to those who have much to do with the determination of acids and alkalies, I have subjected "orange 3" and litmus to a careful comparison. selected it instead of tropaolin, as it is much more delicate in its reactions.

I

Different specimens of litmus somewhat vary in their sensitiveness to acids and alkalies; that with which I

Standard Hydrochloric Acid used. Cub. centims. 28.50

0*00697

Indicator used.

It is obvious, therefore, that the new indicator can be employed in the determination of ammonia instead of litmus, and has many advantages over it.

The Banana.-M. Corenwinder.-The total sugar in this fruit when ripe and sound exceeds 20 per cent, threefourths of which are crystallisable. When over-ripe the total sugar is reduced to from 16 to 14 per cent, whilst the non-crystallisable sugar rises to 11 or 12, thus being not merely relatively but positively increased. - Comptes Rendus.

CHEMICAL NEWS, March

IT was stated some time back (Scientific Notes, Quarterly Journal of Science, April, 1877) that the use of oxide of zinc in the manufacture of caoutchouc nipples for milkbottles has almost been abandoned.

This led to the exam nation of some caoutchouc nipples lately imported from England, and supplied by first-class houses. The examination was afterwards extended to samples of tubing supplied for chemists' use, and a few other caoutchouc goods.

Some specimens of chemists' tubing were found to consist solely of india-rubber and sulphur. Others contained a large proportion of carbonate of lime and a considerable quantity of oxide of zinc, also a little siliceous matterapparently French chalk. Oxide of zinc was present in very large quantity in all the other goods, and siliceous matter never altogether absent.

The following were more particularly examined :—

Lot No. 1.-Oval-shaped nipples, stamped F.

No. 2.-Oval-shaped nipples, stamped J.

No. 3.-Cylindrical nipples, numbered by maker

2, 3, 4.

LIBRARY

CHICÁN

ersity o

from different parts, 65.58 per cent. Carbonate of II 10 per cent. Oxide of zinc, two estimates from rage sample:

Certain acids, when brought in contact with these com

positions, were found to produce some curious phenomena, which will be fully described further on. The acids employed were

hydrous acid.

They were employed of the above strengths, and also much weaker, the dilutions being carried out by volume. The ounce will be understood to mean a fluid ounce. The phenomena alluded to are—

1. Distension of the material from absorption of fluid. 2. The appearance of small elevations on the surface. 3. Crimping of the edges.

These effects appear to be due to the following causes :— 1. The acid has a strong tendency to enter the pores of the material, in consequence of its affinity for the lime or oxide of zinc.

2. Certain acids (notably acetic acid) not only acts solvent on the mineral matters, but also softens the caoutchouc, rendering it in consequence more easy of distension, and at the same time diminishing its power of contracting after distension. The minute state of division in which the vulcanised rubber is left after disintegration of the mineral matter seems to favour this action.

3. The acid entering the pores of the softened material more readily than the solution of zinc or lime salt formed within the pores escapes from them, distension follows.

4. Small elevations will generally appear on the surface of the material, because the distension at first is merely superficial. These elevations are also sometimes produced by escaping gas-bubbles.

If a sharp edge is presented to the action of the acid, crimping of the edge will result, and remain apparent until the action has proceeded to some depth below the surface of the material, and distension has in consequence become more general. The general effects produced by the acids are described below, and a few examples given of the absorption occasioned by acetic acid, &c. Strictly comparable experiments could not be made with the samples at my disposal

Ist. 2nd.

29.01 per cent. 29.18 per cent. Lot No. 5.

Surface very rough and easily abraded. Composition not quite homogeneous. Ash, estimated from sample cut

the irregular form, unequal thickness, and various degrees of elasticity.

The appearance which most samples present under the action of acetic acid is very beautiful, especially if observed with a lens. The phenomenon soon becomes apparent to the naked eye, except with extremely dilute acid; but a lens is required to observe it in the early stage, and to

100

render visible that fine crimping of the edges which constitutes the only apparent effect produced by very weak acid. With the aid of a good watchmaker's eye-glass I have never failed (in numerous trials) to detect the presence of I part of anhydrous acetic acid in 3000 parts of water, by immersing a small piece of nipple (weighing 2 or 3 grains) from Lot No. 1 in 10 c.c. of the diluted acid. Distinct crimping was observed with the lens after twelve to twenty-four hours, when the experiment was performed at the ordinary temperature of the laboratory* (78° to 82° F.). If the fluid and sample were heated on the water-bath, in a closed bottle, the reaction was generally obtained in two or three hours.

It is probable that formic acid will be found to produce the same effect, and that the reaction may be rendered available as a means of detecting minute quantities of either acid in the free state in the absence of the other, provided free mineral acids in large quantity are also absent.

I should here observe that all samples of the material will not be found equally sensitive to the action of the acid, a marked difference being observed in some instances between two samples of apparently the same composition.

Action of Sulphuric Acid.

The strong acid decomposes the material in a few hours. Some specimens were observed to crimp slightly when first immersed, others not at all.

Acid 1 in 2 was found to dissolve out oxide of zinc pretty freely, except from those samples which contained a notable quantity of carbonate o. lime. After twelve days' immersion in acid of this strength the elasticity of the material seemed but slightly impaired. Not the slightest crimping was produced, nor was weaker acid found to occasion it. Acid 1 in 20 dissolved out enough zinc from most samples to be readily detected in the fluid after thirty-six hours' immersion.

Action of Hydrochloric Acid.

A piece of No. I was immersed in about four times its weight of strong acid. In half an hour a notable quantity of zinc was found in solution. Pieces of No. I and No. 5 were immersed in excess of strong acid and examined with lens. Numerous gas-bubbles from No. 5,

Action of Nitric Acid.

CHEMICAL NEWS,

{ March 7, 1879.

The strong acid reduces the material to pulp in a few hours. Acid I in 5 also effects decomposition, though much more slowly. A piece of No. 1 weighing 20 grains was immersed in half an ounce of acid of this strength, and finally examined after eighty hours (slight crimping had been observed in the interval). On cutting, decomposition was found to have advanced to a considerable depth, leaving apparently only sulphur on both surfaces, which formed a brittle crust. Acid 1 in 10 appeared to have little action beyond dissolving out the metallic oxides and slightly softening the caoutchouc, producing effect of this kind could be obtained with acid weaker crimping and general distension of the material. No than I in 100, and very careful inspection with a strong lens was required to observe the faint traces of crimping produced when the most sensitive samples were immersed in acid of this degree of dilution.

Action of Acetic Acid.

Acid of the strength employed in these experiments (or weaker) was found to have very little action on pure vulcanised rubber. Pieces of tubing (composed of the latter) left floating in the acid for days appeared quite unaltered. On mixing the fluid with water, however, it produced milkiness, showing that a small quantity of caoutchouc had gone into solution. The fact that acetic acid has very little action on pure vulcanised rubber renders its extremely energetic action on the mineralised article truly remarkable, especially when it is remembered that as compared with mineral acids its affinity for bases is feeble.

The strong acid dissolves out the mineral matter very readily, and produces distension so rapidly that no elevations appear on the surface of the material, and very slight crimping of the edges is observed.

Distension, however, although it occurs more rapidly with strong than with weak acid, is often sooner arrested with the former than with the latter, and long before the acid has become exhausted. It appears to cease as soon as the fluid contains a certain proportion of salts in solution. From this it follows that a weak acid, other things being equal, may produce as great or greater distension after a time than a strong one. There are, however, so many circumstances that might influence the result (notably the degree of elasticity possessed by the material) that I should hesitate to accept this as the correct view without further and more exact experiments than I have as yet been able to undertake.

After nine days faint traces of crimping observed with lens. After fourteen days these had nearly disappeared. Removed sample. Washed, dried with towel, and weighed.

A piece of nipple from Lot No. 2, weighing 28.72 grs., was immersed in 5 ounces of acid, 1 in 300. After a month the sample was removed, and placed in 5 ounces of fresh acid of the same degree of dilution. The sample was weighed forty-six days after the commencement of the experiment.

Weight, 112 18 grs. Apparent gain, 83'46 grs. The material could be torn rather easily. A portion ignited left a considerable residue of oxide of zinc.

Lot No. 2, piece weighing 10'83 grs. Lot No. 6, piece weighing 8.10 grs. Immersed together in 1 ounce of the strong acid. Weights after twenty-one days :

No. 2, 19.80 grs. Apparent gain, 8'97 grs.
No. 6, 17:30 grs.
9'20 grs.

Lot No. 1.-Nipple cut in two lengthwise. Weight, 23.59 grs., immersed in 2 ozs. acid, 1 in 10. Weight after fourteen days:

93 60 grs. Apparent gain, 70'01 grs. Quantity of oxide of zinc fonnd in 1 ounce of the fluid, 3.78 grs. Material very tender.

NEWS

Lot No. 1.-Nipple cut in two lengthwise. Weight, 27.89 grs. Immersed in 2 ozs. acid, 1 in 50. Weight after fourteen days :

138.70 grs. Apparent gain, 110.81 grs. Quantity of oxide of zinc found in 1 ounce of the fluid, 143 grs. Material very tender.

Lot No. 2.-Nipple cut in two lengthwise. Half immersed in 2 ozs. acid, 1 in 10; the other half in 2 ozs. acid, 1 in 50. Original weight of half in acid 1 in 10, 19'97 grs. Weight after fifteen days:

73 30 grs. Apparent gain, 53'33 grs. Original weight of half in acid 1 in 50, 15'19 grs. Weight after fifteen days :

72.80 grs. Apparent gain, 57'61 grs.

The halves presented originally very nearly, if not quite, the same extent of surface, the difference in weight being due to difference in thickness. After being acted on by the acid, the material in both experiments was found extremely tender.

After this considerable distension fluid escapes so rapidly from the pores of the material, on removal from the acid, that the weight obtained only approximately represents the amount of absorption that has taken place.

The amount of mineral matter dissolved out must also be taken into account. If left to dry these distended samples gradually contract to about their former dimensions, but never recover their elasticity unless the action of the acid has been only slight.

In reference to the phenomena of crimping, &c., by far the finest effects are produced by a dilute acid, say 1 in 300. The result obtained in the following experiment (one out of a very large number tried) will serve to illustrate the action of acid of this strength on a fairly sensitive sample of the material:

Lot No. 1.-Nipple with top cut off; weight 17'9 grs. Lot No. 6.-Piece of tubing cut off; weight 9 gis. Immersed both in oz. acid, 1 in 300. Examined after twelve hours:

No. 1. Decidedly but finely crimped on cut edge, quite apparent to naked eye. Surfaces slightly raised. A few bubbles.

No. 6.-Edges slightly crimped. Requires lens to see distinctly. Surfaces very slightly raised. After thirty-six hours :

No. 1.-Beautifully and finely crimped. Base ring looks like fine sponge. Exterior surface covered with small round elevations, beautifully regular. Interior surface very slightly raised. No bubbles. No. 6.-Edges rather strongly crimped. Surface slightly

raised. No bubbles.

an

LAST Monday will henceforth be looked upon as interesting point of departure in the history of the British Museum Library, for on that day its manifold treasures were for the first time thrown open by night as well as by day to those entitled to use them.

of the Paris Société d'Electricité, assisted by their respective staffs, have been making repeated experiments on the practicability of lighting up the British Museum ReadingRoom by means of the Jablochkoff system of electrical illumination. Having partially determined upon the number and position of the lamps to be used, Mr. Bond decided that on the Monday, Tuesday, and Wednesday of the present week the Reading-room should be kept open until seven o'clock, so that the holders of reading-tickets might have the opportunity of practically testing the value of the welcome innovation. On Monday evening, accordingly, about two hundred readers remained behind after the usual hour for closing, and when, at a few minutes before six o'clock, the twelve Jablochkoff candles in shades of opal glass suddenly burst into light, those present forgot for the moment that they were in a building devoted to silence and study, and evinced their approval of the efforts of the Museum officials on their behalf by breaking into a burst of applause, a sound which we will venture to say has never before been heard beneath Sir Antonio Panizzi's famous dome.

Roughly speaking the Reading-Room is a circle, nineteen-twentieths of which are devoted to the public, the remaining twentieth forming the passage into the Library. In the centre there are three circular desks, the inner one being used for the delivery and return of books, and the two others, which are breast high, for stacking and using the voluminous catalogues. From these run radially nineteen desks divided lengthways by a partition, and lettered from A to T both inclusive, but missing Q, seventeen of which are double, the two end ones being single. At present the first four, A, B, C, and D, are each illuminated by a Jablochkoff lamp, placed on a standard fifteen feet high, fixed exactly in the middle of each desk, being sustained by the longitudinal partition which separates the readers, the remaining fifteen desks being lighted by seven lamps placed alternately. The remaining lamp is placed in the centre of the room, and lights the desks of the Superintendent and his assistants. The general opinion amongst the readers appears to be one of unanimous approbation of this mode of lighting. We have thoroughly tested the matter in a practical manner by reading, writing, tracing, drawing, and painting at one of the first four desks as well as at those which are only lighted alternately. In the first case there is abundant light for comfortable working at any part of the four desks, but in the latter a reader sitting at either end of the illuminated desks has to twist himself round most uncomfortably to get out of his own shadow. We venture to think, therefore, that for the new mode of lighting to be thoroughly satisfactory to all, the whole of the nineteen desks must each be provided with a lamp, thus rendering the imitation of daylight as perfect as need be.

soft, and most agreeable to work by. Now and then, it is It is agreed on all hands that the light is mellow and true, there is a sudden flutter in the light, and occasionally it waxes and wanes slightly, but these defects will no doubt disappear when everything is in full working order.

machine of the latest construction, worked by a Robey The source of electricity is a 20-light duplex Gramme portable engine of 16 horse-power nominal. There are four circuits of five lamps, but only sixteen are used at present; that is to say, twelve in the Reading-Room, one in the Entrance Hall, one under the portico, and two in the machine and engine-shed. The machine and its engine are placed outside in a wooden erection at the north-west corner of the Museum buildings, about 200 yards distant from the Reading Room.