Chapter II: Part 2

These instruments were, therefore, selected for the further experiments, which consisted of using local extensions in Paris and London. The wires were in the first instance extended at the Paris end to the Observatory through an exchange at the Avenue des Gobelines. The length of this local line is 7 kms. The wires are guttapercha-covered, placed underground, and not suitable for giving the best results.

The results were, however, fairly satisfactory. The wires were extended to the Treasury in London by means of the ordinary underground system. The distance is about two miles, and although the volume of sound and clearness of articulation were perceptibly reduced by these additions to the circuit, conversation was quite practicable.

Further trials were also made from the Avenue des Gobelines on underground wires of five kilometers long, and also with some renters in Paris with fairly satisfactory results. The selected telephones were equally efficient in all cases, which proves that to maintain easy conversation when the trunk wires are extended to local points it is only necessary that the local lines shall be of a standard not lower than that of the trunk line. The experiments also confirm the conclusion that long-distance speaking is solely a question of the circuit and its environments, and not one of apparatus. The instruments finally selected for actual work were Gower-Bell for London and Roulez for Paris.

3. The results are certainly most satisfactory. There is no circuit in or out of London on which speech is more perfect than it is between London and Paris. In fact, it is better than I anticipated, and better than calculation led me to expect. Speech has been possible not only to Paris but through Paris to Bruxelles, and even, with difficulty, through Paris to Marseilles, a distance of over 900 miles. The wires between Paris and Marseilles are massive copper wires specially erected for telephone business between those important places.

4. _Business Done._--The charge for a conversation between London and Paris is 8 s. for three minutes' complete use of the wire. The demand for the wire is very considerable. The average number of talks per day, exclusive of Sunday, is 86. The maximum has been 108. We have had as many as 19 per hour--the average is 15 during the busy hours of the day. As an instance of what can be done, 150 words per minute have been dictated in Paris and transcribed in London by shorthand writing. Thus in three minutes 450 words were recorded, which at 8 s. cost five words for a penny.

5. _Difficulties._--The difficulties met with in long-distance speaking are several, and they may be divided into (a) those due to external disturbances and (b) those due to internal opposition.

(_a._) Every current rising and falling in the neighborhood of a telephone line within a region, say, of 100 yards, whether the wire conveying it be underground or overground, induces in the telephone circuit another current, producing in the telephone a sound which disturbs speech, and if the neighboring wires are numerous and busy, as they are on our roads and railways, these sounds became confusing, noisy, and ultimately entirely preventive of speech. This disturbance is, however, completely removed by forming the telephone circuit of two wires placed as near to each other as possible, and twisted around each other without touching, so as to maintain the mean average distance of each wire from surrounding conductors the same everywhere. Thus similar currents are induced in each of the two wires, but being opposite in direction, as far as the circuit is concerned, they neutralize each other, and the circuit, therefore, becomes quite silent.

In England we make the two wires revolve completely round each other in every four poles, but in France it is done in every six poles. The reason for the change is the fact that in the English plan the actual crossing of the wires takes place in the span between the poles, while in the French plan it takes place at the poles. This is supposed to reduce the liability of the wires to be thrown into contact with each other by the wind, but, on the other hand, it diminishes the geometrical symmetry of the wires--so very essential to insure silence. As a matter of fact, contacts do not occur on well constructed lines, and I think our English wires, being more symmetrical, are freer from external disturbance than those in France.

(_b._) The internal opposition arises from the resistance, R, the capacity, K, and the electromagnetic inertia, L, of the circuit. A current of electricity takes time to rise to its maximum strength and time to fall back again to zero. Every circuit has what is called its time constant, _t_, Fig. 1, which regulates the number of current waves which can be transmitted through it per second. This is the time the current takes to rise from zero to its working maximum, and the time it takes to fall from this maximum to zero again, shown by the shaded portions of the figure; the duration of the working current being immaterial, and shown by the unshaded portion.

The most rapid form of quick telegraphy requires about 150 currents per second, currents each of which must rise and fall in 1/150 of a second, but for ordinary telephone speaking we must have about 1,500 currents per second, or the time which each current rises from zero to its maximum intensity must not exceed 1/3000 part of a second. The time constant of a telephone circuit should therefore not be less than 0.0003 second.

Resistance alone does not affect the time constant. It diminishes the intensity or strength of the currents only; but resistance, combined with electromagnetic inertia and with capacity, has a serious retarding effect on the rate of rise and fall of the currents. They increase the time constant and introduce a slowness which may be called retardance, for they diminish the rate at which currents can be transmitted. Now the retardance due to electromagnetic inertia increases directly with the amount of electromagnetic inertia present, but it diminishes with the amount of resistance of the conductor. It is expressed by the ratio L/R while that due to capacity increases directly, both with the capacity and with the resistance, and it is expressed by the product, K R. The whole retardance, and, therefore, the speed of working the circuit or the clearness of speech, is given, by the equation

L
--- + K R = t
R

or L + K R squared = R t

Now in telegraphy we are not able altogether to eliminate L, but we can counteract it, and if we can make Rt = 0, then

L = - K R squared

which is the principle of the shunted condenser that has been introduced with such signal success in our post office service, and has virtually doubled the carrying capacity of our wires.

K R = t

This is done in telephony, and hence we obtain the law of retardance, or the law by which we can calculate the distance to which speech is possible. All my calculations for the London and Paris line were based on this law, which experience has shown it to be true.

How is electromagnetic inertia practically eliminated? First, by the use of two massive copper wires, and secondly by symmetrically revolving them around each other. Now L depends on the geometry of the circuit, that is, on the relative form and position of the different parts of the circuit, which is invariable for the same circuit, and is represented by a coefficient, [lambda]. It depends also on the magnetic qualities of the conductors employed and of the space embraced by the circuit. This specific magnetic capacity is a variable quantity, and is indicated by [mu] for the conductor and by [mu]_{0} for air. It depends also on the rate at which currents rise and fall, and this is indicated by the differential coefficient dC / dt. It depends finally on the number of lines of force due to its own current which cut the conductor in the proper direction; this is indicated by [beta]. Combining these together we can represent the electromagnetic inertia of a metallic telephone circuit as

L = [lambda] ([mu] + [mu]_{0}) dC/dt x [beta]

Now, [lambda] = 2 log (d squared/a squared) Hence the smaller we make the distance, _d_, between the wires, and the greater we make their diameter, _a_, the smaller becomes [lambda]. It is customary to call the value of [mu] for air, and copper, 1, but this is purely artificial and certainly not true. It must be very much less than one in every medium, excepting the magnetic metals, so much so that in copper it may be neglected altogether, while in the air it does not matter what it is, for by the method of twisting one conductor round the other, the magnetization of the air space by the one current of the circuit rotating in one direction is exactly neutralized by that of the other element of the circuit rotating in the opposite direction.

Now, [beta], in two parallel conductors conveying currents of the same sense, that is flowing in the same direction, is retarding, Fig. 2, and is therefore a positive quantity, but when the currents flow in opposite directions, as in a metallic loop, Fig. 3, they tend to assist each other and are of a negative character. Hence in a metallic telephone circuit we may neglect L _in toto_ as I have done.

I have never yet succeeded in tracing any evidence of electromagnetic inertia in long single copper wires, while in iron wires the value of L may certainly be taken at 0.005 henry per mile.

In short metallic circuits, say of lengths up to 100 miles, this negative quantity does not appear, but in the Paris-London circuit this helpful mutual action of opposite currents comes on in a peculiar way. The presence of the cable introduces a large capacity practically in the center of the circuit. The result is that we have in each branch of the circuit between the transmitter, say, at London and the cable at Dover, extra currents at the commencement of the operation, which, flowing in opposite directions, mutually react on each other, and practically prepare the way for the working currents. The presence of these currents proved by the fact that when the cable is disconnected at Calais, as shown in Fig. 5, and telephones are inserted in series, as shown at D and D', speech is as perfect between London and St. Margaret's Bay as if the wires were connected across, or as if the circuit were through to Paris. Their effect is precisely the same as though the capacity of the aerial section were reduced by a quantity, M, which is of the same dimension or character as K. Hence, our retardance equation becomes

R (K - M) = t

Thus it happens that the London-Paris telephone works better than was expected. The nature of M is probably equivalent to about 0.0075 [phi] per mile, and therefore K should be also about 0.0075 [phi] instead of 0.0156 [phi] per mile. This helpful action of mutual induction is present in all long circuits, and it is the reason why we were able to speak to Brussels and even to Marseilles. It also appears in every metallic loop, and vitiates the measurements of electromagnetic inertia and of capacity of loops. Thus, if we measure the capacity of a loop as compared with a single wire, the amount per mile may be 50 per cent. greater than it ought to be; while if we measure the capacity of one branch of a circuit under the conditions of the London-Paris telephone line, it may be 50 per cent. less than it ought to be. This effect of M is shown by the dotted line in Fig. 1.

Telephonic currents--that is, currents induced in the secondary wire of an induction coil due to the variation of microphonic currents in the primary wire--are not alternating currents. They do not follow the constant periodic law, and they are not true harmonic sine functions of the time. The microphonic currents are intermittent or pulsatory, and always flow in the same direction. The secondary currents are also always of the same sign, as are the currents in a Ruhmkorff coil, and as are the currents in high vacua with which Crookes has made us so familiar. Moreover, the frequency of these currents is a very variable quantity, not only due to the various tones of voices, but to the various styles of articulation. Hence the laws of periodic alternate currents following the sine function of the time fail when we come to consider microphones and telephones. It is important to bear this in mind, for nearly everything that has hitherto been written on the subject assumes that telegraphic currents follow the periodic sine law. The currents derived from Bell's original magneto-transmitters are alternate, and comply more nearly with the law. The difference between them and microphones is at once perceptible. Muffling and disturbance due to the presence of electromagnetic inertia become evident, which are absent with microphones. I tested this between London and St. Margaret's, and found the effect most marked.

7. _Lightning._--A metallic telephone circuit may have a static charge induced upon it by a thunder cloud, as shown in Fig. 6. Such a charge is an electric strain which is released when the charged cloud flashes into the earth or into a neighboring cloud. If there be electromagnetic inertia present, the charge will surge backward and forward through the circuit until it dies out. If there be no E.M.F. present it will cease suddenly, and neutrality will be attained at once. Telephone circuits indicate the operation by peculiar and characteristic sounds. An iron wire circuit produces a long swish or sigh, but a copper wire circuit like the Paris-London telephone emits a short, sharp report, like the crack of a pistol, which is sometimes startling, and has created fear, but there is no danger or liability to shock. Indeed, the start has more than once thrown the listener off his stool, and has led to the belief that he was knocked down by lightning.

8. The future of telephone working, especially in large cities, is one of underground wires, and the way to get over the difficulties of this kind of work is perfectly clear. We must have metallic circuits, twisted wires, low resistance, and low capacity. In Paris a remarkable cable, made by Fortin-Herman, gives an exceedingly low capacity--viz., only 0.069 [phi] per mile. In the United States they are using a wire insulated with paper which gives 0.08 [phi] per mile. We are using in London Fowler-Waring cable giving a capacity of 1.8 [phi] per mile, the capacity of gutta-covered wire being 3 [phi] per mile.

* * * * *

THE MANUFACTURE OF PHOSPHORUS BY ELECTRICITY.

One of the most interesting of the modern applications of electricity to the manufacture of chemicals is to be found in the recently perfected process known as the Readman-Parker process, after the inventors Dr. J.B. Readman, F.R.S.E., etc., of Edinburgh, and Mr. Thomas Parker; the well known practical electrician, of Wolverhampton.

Before giving an account of this process, which has advanced beyond the experimental to the industrial stage, it may be well to recall the fact that for several years past Dr. Readman has been devoting an enormous expenditure of labor, time and money to the perfection of a process which shall cheapen the production of phosphorus by dispensing altogether with the use of sulphuric acid for decomposing the phosphate of lime which forms the raw material of the phosphorus manufacturer, and also with the employment of fire clay retorts for distilling the desiccated mixture of phosphoric acid and carbon which usually forms the second stage of the operation.

The success of the recent applications of electricity in the production of certain metals and alloys led Dr. Readman to try this source of energy in the manufacture of phosphorus, and the results of the first series of experiments were so encouraging that he took out provisional protection on October 18, 1888, for preparing this valuable substance by its means.

The experiments were carried on at this time on a very small scale, the power at disposal being very limited in amount. Yet the elements of success appeared to be so great, and the decomposition of the raw material was so complete, that the process was very soon prosecuted on the large scale.

After a good deal of negotiation with several firms that were in a position to supply the electric energy required, Dr. Readman finally made arrangements with the directors of the Cowles Company, limited, of Milton, near Stoke-on-Trent, the well known manufacturers of alloys of aluminum, for a lease of a portion of their works and for the use of the entire electrical energy they produced for certain portions of the day.

The experiments on the large scale had not advanced very far before Dr. Readman became aware that another application for letters patent for producing phosphorus had been made by Mr. Thomas Parker, of Wolverhampton, and his chemist, Mr. A.E. Robinson. Their joint patent is dated December 5, 1888, and was thus applied for only seven weeks after Dr. Readman's application had been lodged.

It appeared that Mr. Parker had conducted a number of experiments simultaneously but quite independently of those carried on by Dr. Readman, and that he was quite unaware--as the latter was unaware--of any other worker in this field. It was no small surprise, therefore, to find during an interview which took place between these rival inventors some time after the date referred to, that the two patents were on practically the same lines, namely, the production of phosphorus by electricity.

Their interests lay so much together that, after some delay, they arranged to jointly work out the process, and the result has been the formation of a preliminary company and the erection on a large scale of experimental plant in the neighborhood of Wolverhampton to prove the commercial success of the new system of manufacturing phosphorus.

Before describing these experimental works it may be as well to see with what plant Dr. Readman has been working at the Cowles Company's works. And here we may remark that we are indebted to a paper read by Dr. Readman at the Philosophical Institution, Edinburgh, a short time ago; this paper being the third of a series which during the last year or two have been read by the same scientist on this branch of chemical industry. Here is an abstract giving a description of the plant. The works are near the Milton Station, on the North Staffordshire Railway. The boilers for generating the steam required are of the Babcock-Wilcox type, and are provided with "mechanical stokers;" the steam engine is of 600 horse power, and is a compound condensing horizontal tandem, made by Messrs. Pollitt & Wigzel, of Sowerby Bridge. The fly wheel of this engine is 20 feet in diameter, and weighs 30 tons, and is geared to the pulley of the dynamo, so that the latter makes five revolutions for each revolution of the engine by rope driving gear, consisting of eighteen ropes. The engine is an extremely fine specimen of a modern steam engine; it works so silently that a visitor standing with his back to the engine railings, at the time the engine is being started, cannot tell whether it is in motion or not.

With regard to the dynamo, the spindle is of steel, 18 feet long, with three bearings, one being placed on either side of the driving pulley. The diameter is 7 inches in the bearings and 10 inches in the part within the core. This part in the original forgings was 14 inches in diameter, and was planed longitudinally, so as to leave four projecting ribs or radial bars on which the core disks are driven, each disk having four key ways corresponding to these ribs. There are about 900 of these disks, the external diameter being 20 inches and the total length of the core 36 inches.

The armature winding consists of 128 copper bars, each 7/8 in. deep, measured radially, by 3/8 in. wide. These bars are coupled up so as to form thirty-two conductors only; this arrangement has been adopted to avoid the heating from the Foucault currents, which, with 11/2 in. conductors, would have been very considerable. The bars are coupled at the ends of the core across a certain chord and are insulated.

The commutator is 20 inches long, and has sixty-four parts. The current is collected by eight brushes mounted on a separate ring, placed concentric to the commutator; and the current is led away from these brushes by a large number of thin bands of sheet copper strapped together into convenient groups. The field magnets are of the horizontal double type.

As this machine is virtually a series wound machine, the magnet coils each consist of a few turns only of forged copper bars, 11/2 in. wide by 1 in. thick, forged to fit the magnet cores.

There is no insulation other than mica wedges to keep the bars from touching the core.

The dynamo furnishes a current of about 5,000 amperes, with an E.M.F. of 50 to 60 volts, and three years ago was claimed to be the largest machine, at least as regards quantity of current, in the world.

The current from the dynamos is led by copper bars to an enormous "cut out," calculated to fuse at 8,000 amperes. This is probably one of the largest ever designed, and consists of a framework carrying twelve lead plates, each 31/2 in. x 1/16th in. thick. A current indicator is inserted in the circuit consisting of a solenoid of nine turns. The range of this indicator is such that the center circle of 360 deg.=8,000 amperes.

The electrodes consisted of a bundle of nine carbons, each 21/2 in. in diameter, attached by casting into a head of cast iron. Each carbon weighs 20 lb, and, when new, is about 48 inches long.

The head of the electrode is screwed to the copper rods or "leads," which can be readily connected with the flexible cable supplying the current.

The electric furnaces are rectangular troughs built of fire brick, their internal dimensions being 60 in. x 20 in. x 36 in. deep. Into each end is built a cast iron tube, through which the carbon electrodes enter the furnace.

The electrodes are so arranged that it is possible by means of screwing to advance or withdraw them from the furnace.

The whole current generated by the great dynamo of the Cowles Company was passed through the furnace.

In the experiments raw materials only were used, for it was evident that it was only by the direct production of phosphorus from the native minerals which contain it, such as the phosphates of lime, magnesia, or alumina that there was any hope of superseding, in point of economy, the existing process of manufacture.

In the furnaces as used at Milton much difficulty was experienced in distributing the heat over a sufficiently wide area. So locally intense indeed was the heat within a certain zone, that all the oxygen contained in the mixture was expelled and alloys of iron, aluminum, and calcium combined with more or less silicon, and phosphorus were produced. Some of these were of an extremely interesting nature.

We now turn to a short account of the works and plant which have been erected near Wolverhampton to prove the commercial success of the new system of manufacturing phosphorus.

The ground is situated on the banks of a canal and extends to about 10 acres, which are wholly without buildings except those which have been erected for the purposes of these industrial experiments. These consist of boiler and engine houses, and large furnace sheds.

There are three Babcock & Wilcox steam boilers of 160 horse power each, and each capable of evaporating 5,000 lb. of water per hour. The water tubes are 18 ft. long x 4 inches diameter, and the steam and water drums 43 in. in diameter and 231/2 ft. long, of steel 7/16 ths. in. thick, provided with a double dead head safety valve, stop valves, blow-off cock, water gauges, and steam gauge.

The total heating surface on each boiler is 1,619 square feet and the total grate surface is 30 square feet.

The boilers are worked at 160 lb. pressure.

The engine is a triple compound one of the type supplied for torpedo boats, and built by the Yarrow Shipbuilding Company. It is fitted with a Pickering governor for constant speed. The engine is capable of delivering (with condenser) 1,200 indicated horse power, and without condenser 250 indicated horse power less.

With steam at 170 lb. pressure the engine worked at 350 revolutions per minute, but it has been rearranged so as to deliver 700 indicated horse power with 160 lb. steam pressure without condenser, and at 300 revolutions per minute:

The high pressure cylinder is 141/2 inches diameter.
" intermediate " " 25 " "
" low pressure " " 32 " "
" stroke is 16 inches.

The dynamo for producing the requisite amount of electric current supplied to the furnaces is one of the well known Elwell-Parker type of alternating current dynamos, designed to give 400 units of electrical energy, equivalent to 536 indicated horse power.

The armature in the machine is stationary, with double insulation between the armature coils and the core, and also between the core and the frame, and is so arranged that its two halves may be readily connected in series or in parallel in accordance with the requirements of the furnaces, e.g., at an electromotive force of 80 volts it will give 5,000 amperes, and at 160 volts, 2,500 amperes when running at 300 revolutions per minute.

The exciting current of the alternator is produced by an Elwell-Parker shunt wound machine, driven direct from a pulley on the alternator shaft, and so arranged as to give 90 amperes at 250 volts when running at a speed of 800 revolutions per minute. From 60 to 70 amperes are utilized in the alternator, the remainder being available for lighting purposes (which is done through accumulators) and general experimental purposes.

The process is carried out in the following way: The raw materials, all intimately and carefully mixed together, are introduced into the furnace and the current is then turned on. Shortly afterward, indications of phosphorus make their appearance.

The vapors and gases from the furnace pass away to large copper condensers--the first of which contains hot and the second cold water--and finally pass away into the air.

As the phosphorus forms, it distills off from the mixture, and the residue forms a liquid slag at the bottom of the furnace. Fresh phosphorus yielding material is then introduced at the top. In this way the operation is a continuous one, and may be continued for days without intermission.

The charges for the furnace are made up with raw material, i.e., native phosphates without any previous chemical treatment, and the only manufactured material necessary--if such it may be called--is the carbon to effect the reduction of the ores.

The crude phosphorus obtained in the condensers is tolerably pure, and is readily refined in the usual way.

Dr. Readman and Mr. Parker have found that it is more advantageous to use a series of furnaces instead of sending the entire current through one furnace. These furnaces will each yield about 11/2 cwt. of phosphorus per day.

Analyses of the slag show that the decomposition of the raw phosphates is very perfect, for the percentage of phosphorus left in the slag seldom exceeds 1 per cent.--_Chemical Trade Journal_.

* * * * *

NEW BLEACHING APPARATUS.

The apparatus forming the subject of this invention was designed by Francis A. Cloudman, Erwin B. Newcomb, and Frank H. Cloudman, of Cumberland Mills, Me., and comprises a series of tanks or chests, two or more in number, through which the material to be bleached is caused to pass, being transferred from one to the next of the series in order, while the bleaching agent is caused to pass through the series of chests in the reverse order, and thus acts first and at full strength upon the materials which have previously passed through all but the last one of the series of chests and have already been subjected to the bleaching agent of less strength.

For convenience, the chest in which the material is first introduced will be called the "first of the series" and the rest numbered in the order in which the material is passed from one to the other, and it will be understood that any desired number may be used, two, however, being sufficient to carry on the process.

The invention is shown embodied in an apparatus properly constructed for treating pulp used for the manufacture of paper, and for convenience the material to be bleached will be hereinafter referred to as the pulp, although it is obvious that similar apparatus might be used for bleaching other materials, although the apparatus might have to be modified to adapt it for conveying other materials of different nature than pulp from one bleaching chest to the other and for separating out the bleaching liquid and conveying it from one chest to the other in the reverse order to that in which the material passes from one chest to the next.

The pulp material with which the apparatus herein illustrated is intended to be used is retained in suspension in the bleaching liquid and flows readily through ducts or passages provided for it in the apparatus in which the pulp to be bleached and the bleaching liquid are introduced together at the bottom of each chest and flow upward therethrough, while at the top of each chest there are two conveyors, one for carrying the pulp from one chest to the next in order, while the other carries the bleaching liquid from one tank to the next in the reverse order, the said conveyors also acting to partially separate the pulp from the liquid in which it has been suspended during its upward passage through the chest.

Suitable agitators may be employed for thoroughly mixing the materials in the chest and in the apparatus shown the bleaching agent and material to be bleached pass through each chest in the same direction--namely from the bottom to the top--although they are carried from one chest to the next in the reverse order, the material to be bleached being primarily introduced into the chest at one end of the series, while the bleaching agent or solution is introduced primarily into the chest at the other end of the series.

Fig. 1 is a plan view of an apparatus for bleaching in accordance with this invention, comprising a series of four chests, and Fig. 2 is a vertical longitudinal section of a modified arrangement of two chests in line with one another, and with the conveyor for the material to be bleached and the passage through which said material passes from the top of one chest into the bottom of the next chest in the plane of section.

The chests, _a_ _a2_ _a3_ _a4_, may be of any desired shape and dimensions and any desired number may be used. Each of said chests is provided with an inlet passage, _b_, opening into the same near its bottom, and through this passage the materials are introduced. The unbleached material, which may be paper pulp or material which is readily held in suspension in a liquid and is capable of flowing or being conveyed from one point to another in a semi-fluid condition, is introduced through the inlet passage, _b_, to the first chest, _a_, of the series, said pulp preferably having had as much as possible of the liquid in which it was previously suspended removed without, however, drying it, and, together with the said pulp, the bleaching agent which has previously passed through the other chests of the series, as will be hereinafter described, is introduced so that both enter together at the lower portion of the first chest, _a_, of the series. The said materials are caused to flow into the chest continuously, so that the portion at each moment entering tends to displace that which has already entered, thus causing the materials to rise gradually or flow upward from the bottom to the top of the chest.

Suitable stirring devices or agitators, _c_, may be employed to keep the pulp in suspension and to expose it thoroughly and uniformly to the liquid introduced with it.

When the materials (the pulp and the bleaching liquid) arrive at or near the top of the chest, they are partially separated from one another and removed from the chest at substantially the same rate that they are introduced, as follows: Each chest is provided at its upper part with a liquid conveyor, _d_, having a construction similar to that of the device known as a "washer" in paper making machinery, consisting of a rotating drum, the periphery of which is covered with gauze, which permits the liquid to pass into it, but excludes the pulp suspended in the liquid, the said drum containing blades or buckets that raise the liquid which thus enters through the gauze and discharges it at _d2_ near the axis of said drum. There is one of these washers in each one of the series of chests, and each discharges the liquid taken from its corresponding chest into the inlet pipe of the next preceding chest of the series, the washer in the chest, _a4_, for example, delivering into the inlet passage, _b_, of the chest, _a2_, and so on, while the washer of the first chest, _a_, of the series delivers into a discharge pipe, _e_, through which the liquid may be permitted to run to waste or conveyed to any suitable receptacle, if it is desired to subject it to chemical action for the purpose of renewing its bleaching powers or obtaining the chemical agents that may be contained within it.

The operation of the washers in removing the liquid from the upper part of the chest tends to thicken the pulp therein, and the said thickened pulp is conveyed from one chest to the next in the series by any suitable conveying device, _f_ (shown in this instance as a worm working in a trough or case, _f2_), which may be made foraminous for the purpose of permitting the liquid to drain out of the pulp that is being carried through by the worm, in order that the pulp may be introduced into the next chest of the series as free as possible from the liquid in which it has been suspended while in the chest from which it is just taken. The pulp is thus conveyed from one chest in the series to the inlet passage leading to the next chest of the series, and in the said inlet passage it meets the liquid coming in the reverse order from the next chest beyond in the series, the pulp and liquid thus commingling in the inlet pipe and entering the chest together, and being thoroughly mixed by the agitators in passing through the chest by the continued action of fresh material entering and of the conveyors taking the material out from the chests. In the last of the series of chests into which the pulp is introduced the fresh or strong bleaching liquid is introduced through a suitable inlet pipe, _g_, and the pulp conveyor, _f_, that takes the pulp from the last chest, delivers it into a pipe, _h_, by which it may be conveyed to any desired point, the said pulp having been sufficiently bleached before arriving at the said pipe, _h_. It will be seen that by these means all the pulp is thoroughly and uniformly subjected to the bleaching agent and that the bleaching is gradually performed in all parts of the pulp, which is first acted upon by the weaker bleaching agent that has previously operated upon the pulp before treated, and that finally, when nearly bleached, the pulp is acted upon by the bleaching material of full strength, this action being far more efficient than when the materials are simply mixed together, the unbleached material with the strong bleaching agent, and allowed to remain together until the bleaching operation is finished, in which plan the bleaching agent loses its strength as the bleaching operation approaches completion, so that when the pulp is nearly bleached it is operated upon by a very weak bleaching agent. By having the pulp transferred from one chest to the next in the reverse order to that in which the liquid is transferred it will be seen that all parts of the pulp are acted upon uniformly and equally and that the operation may go on continuously for an indefinite period of time without necessitating stopping to empty the vats, as is the case when the liquor only is transferred from one vat to the next. A pump may be used for lifting the bleaching liquid, as shown, for example, at _k_, Fig. 1. where said pump is used to raise the liquid delivered from the chest, _a2_, and discharge it into the trough, _m_, by which the pulp is carried to the inlet pipe, _b_. By the use of the pump, _h_, a stronger flow of the liquid into the pipe _b_, of the first chest, _a_, is effected than if it were taken directly from the washer of the chest, _a2_, which is desirable, as the pulp is delivered in the trough, _m_, with but little moisture.

It is obvious that the construction of the apparatus may be varied considerably without materially changing the essential features of operation. For example, the washers might be dispensed with and the liquid permitted to flow through suitable strainers from one chest to the next in order, by gravity, the successive chests in the order of the passage of the pulp being placed each at a higher level than the preceding one, and it is also obvious that the construction of the pulp conveyors might be widely varied, it being essential only that means should be provided for removing the pulp from one chest and delivering it into the next while carrying only a small amount of the liquid from one chest to the next with the pulp.

* * * * *

THE USE OF COMPRESSED AIR IN CONJUNCTION WITH MEDICINAL SOLUTIONS IN THE TREATMENT OF NERVOUS AND MENTAL AFFECTIONS.

BEING A NEW SYSTEM OF CEREBRO-SPINAL THERAPEUTICS.

By J. LEONARD CORNING, A.M., M.D., New York, Consultant in Nervous Diseases to St. Francis Hospital, St. Mary's Hospital, the Hackensack Hospital, etc.

To merely facilitate the introduction of medicinal agents into the system by way of the air passages, in the form of gases, medicated or non-medicated, has heretofore constituted the principal motive among physicians for invoking the aid of compressed air. The experiments of Paul Bert with nitrous oxide and oxygen gas, performed over fourteen years ago, and the more recent proposals of See, are illustrations in point.

The objects of which I have been in search are quite different from the foregoing, and have reference not to the introduction of the remedy, but to the enhancement of its effects after exhibition. Let me be more explicit on this point, by stating at once that, in contradistinction to my predecessors, I shall endeavor to show that by far the most useful service derivable from compressed air is found in its ability to enhance and perpetuate the effects of soluble remedies (introduced hypodermically, by the mouth, or otherwise) upon the internal organs, and more especially upon the cerebro-spinal axis. Some chemical affinity between the remedy employed and the protoplasm of the nerve cell is, of course, assumed to exist; and it is with the enhancement of this affinity--this bond of union between the medicinal solution and the nervous element--that we shall chiefly concern ourselves in the following discussion.

By way of introduction, I may recall the fact that my attention was directed several years since to the advisability of devising some means by the aid of which medicinal substances, and more especially anaesthetics, might be made to localize, intensify, and perpetuate their action upon the peripheral nerves. The simple problem in physiology and mechanics involved in this question I was fortunate enough to solve quite a long time ago; and I must confess that in the retrospect these undertakings in themselves do not seem to me of great magnitude, though in their practical application their significance appears more considerable. Herein lies, it may be, the explanation of the interest which these studies excited in the profession at the time of their publication. These things are, however, a part of medical history; and I merely refer to them at this time because they have led me to resume the solution of a far greater problem--that of intensifying, perpetuating, and (to some extent at least) localizing the effects of remedies upon the brain and spinal cord. I speak of resuming these studies because, as far back as 1880 and 1882, I made some attempts--albeit rather abortive--in the same direction.

In constructing the argument for the following study, I am beholden more especially to three facts, the knowledge of which came to me as the direct result of experimental tests. One may place confidence, therefore, in the procedure which I have based upon these premises, for at no point, I think, in the following argument will mere affirmation be found to have usurped the place of sound induction. Without anticipating further, then, let me specify as briefly as may be the nature of these facts.

PREMISES OF ARGUMENT. _First Fact._--The amount of ether, chloroform, chloral hydrate, the bromides, strychnine, and many other remedies, required to produce physiological effects upon the cerebro-spinal mechanism may be reduced by first securing a ligature around the central portion of one or several of the limbs of an animal, so as to interrupt both the arterial and venous circulation.

The proof and explanation of this may be thus presented:

In the first place, it is well known that children and small animals are affected by much smaller quantities of anaesthetics and other medicinal substances than are required to produce equal effects in men and large animals.

At first sight, there appears to exist a certain definite relation between the weight of the animal and the quantity of medicament required to produce physiological effects. On closer inquiry, however, we find behind this proposition the deeper truth that the real proportion is between the magnitude of the blood-mass and the amount of medicament. Thus, if we withdraw a considerable amount of blood from a large dog, we may be able to affect him by much smaller doses than those required under ordinary circumstances; and, among human beings, we find the anaemic much more susceptible to remedies than the full-blooded of equal weight.

The degree of saturation of the blood-mass with the remedy is obviously, then, the principal thing; the greater the amount of blood, the more remedy--everything else being equal--we shall have to give in order to obtain definite results.

If we wish to embody the proposition in a mathematical statement, we may do so in the following simple manner:

Let a represent the total quantity of blood, _b_, the amount of remedy exhibited, and _x_ the magnitude of the physiological effect. We shall then have the simple formula, x = b / a.

Again, if we withdraw a certain quantity of blood from the circulation by venesection, and call that amount _d_, we shall then have the formula x = b / (a-d).

But, if we wish to act upon the organs of the trunk, and more especially upon those contained within the cerebro-spinal canal, it is not necessary to resort to such a drastic expedient as copious blood-letting; for, in place of this, we may dam up and effectually eliminate from the rest of the body a certain amount of blood by passing a ligature around the central portion of one or several extremities, so as to interrupt the circulation in both artery and vein. When this has been done it is clear that we may introduce a remedy into the system by way of the stomach, or hypodermically into some portion of the trunk; and it is equally certain that a remedy so introduced will be diluted only in the ratio of the amount of blood freely circulating, and more especially by that contained within the trunk and head. That which is incarcerated behind the ligatures is as effectually withdrawn from the realm of physiological action as though it had been abstracted by the surgeon's knife. Elimination by the knife and elimination by the ligature are, for present purposes, then, one and the same thing. Hence, if we let _d'_ represent the amount of blood incarcerated behind the ligatures, _x_ the magnitude of the physiological effect which we are seeking, _b_ the amount of remedy exhibited, and a the total amount of blood contained in the whole organism, we shall have the formula,

b b
x = ------ = -----
a - d' a - d

Several years since, I had an excellent opportunity of proving the truth of the foregoing, in connection with the administration of ether in the case of a patient who resisted all attempts to anaesthetize him in the ordinary way.

The case in question was a man under treatment at the Manhattan Eye and Ear Hospital, upon whom it was deemed advisable to perform an operation. As has been said, the ordinary means of inducing anaesthesia had proved ineffectual, for the man was a confirmed drunkard; and it was at this juncture that I was called in consultation and requested by my friend, Dr. David Webster, one of the surgeons of the hospital, to endeavor to devise some means of getting the man under the influence of the anaesthetic.

The procedure which I suggested was this:[3] Around the upper part of each thigh a flat rubber tourniquet was tightly drawn and secured in place in the usual manner. By this means the sequestration of all the blood contained in the lower limbs was accomplished; but, inasmuch as both artery and vein were compressed, only the amount of blood usually contained in each limb was shut off from the rest of the body--which would not have been the case had we contented ourselves with merely compressing the veins, as some have done.

[Footnote 3: On the "Effective and Rapid Induction of General Anaesthesia," the New York _Medical Journal_, October 22 and December 24, 1887.]

In subsequently commenting on my published report of this case, that most accomplished writer and physician, Henry M. Lyman--than whom there is no greater authority on anaesthesia--observes that the plan proposed and adopted by me on this occasion (that of compressing both vein and artery) is far preferable to compression of the vein alone.

The reason for this is not far to seek. When we compress the veins alone there is a rapid accumulation of blood in the extremities through the accessions derived from the uninterrupted arteries. Now, as this blood is derived from the trunk, and consequently also from the organs contained within the cerebro-spinal canal, there is danger of syncope and even heart failure. When, on the other hand, both artery and vein are compressed no such derivative action occurs, and all danger is, consequently, removed. With an apology for this brief digression, I now return to the interesting case which has given rise to it.

Having, as previously stated, applied tourniquets to the central portion of the lower limbs, the ether cap was placed over the mouth and nose of the patient, and in an incredibly short time he was unconscious, and the surgeons were able to go on with the operation.

The late Dr. Cornelius R. Agnew and many other members of the staff of the hospital were present, and gave emphatic expressions of approval.

Dr. F.W. Ring, assistant surgeon to the Manhattan Eye and Ear Hospital, declared that both the amount of ether and the time consumed in its administration were infinitesimal when compared with what had been expended in previous efforts at inducing anaesthesia in the usual way. The facts brought out on this occasion with regard to the administration of ether have since been repeatedly verified by different observers; so that at the present day their validity cannot be questioned. I will merely add, however, that I have long known that the dosage of phenacetin, antipyrine, morphine, chloralamid, chloral, the bromides, and many other remedies might be reduced by resort to the same procedure; all of which is merely equivalent to stating that their pharmaco-dynamic energy may be increased in this way. And this brings us to the second fact, which requires no special elaboration, and may be stated thus:

_Second Fact._--The duration of the effect of a remedy upon the cerebro-spinal axis is in the inverse ratio of its volatility; and this is equally true whether the remedy be given with or without the precautions previously detailed. For example, the anaesthetic effects of ether disappear shortly after removal of the inhaler, whether we apply tourniquets to the extremities or not; but, on the other hand, the analgesic influence of antipyrin, phenacetin, morphine, and other like remedies lasts very much longer, and their dose may be reduced, or--what is the same thing--their pharmaco-dynamic potency may be enhanced by the sequestration of the blood contained within the extremities. So far as I know, I was the first to announce this fact. In so far as a simple expression of the above truth is concerned, we may employ the following formula:

Let _a_ represent the normal blood-mass contained in the entire body, _d_ the amount of blood sequestrated by the ligatures, _b_ the amount of the remedy, _c_ the volatility of the remedy, and _x_ the pharmaco-dynamic potency of which we are in search; we shall then have

b
x = -----------
(a - d') x c

We now arrive at our third fact, which will require more extensive elaboration.

_Third Fact._--The pharmaco-dynamic potency of stimulants, sedatives, analgesics, and probably of all remedies which possess a chemical affinity for nervous matter, is enhanced by exhibiting them (the remedies) in solution or soluble form--hypodermically, by the mouth, or per rectum--while the subject remains in a condensed atmosphere. And, as a corollary, it may be stated that this increase, this enhancement of the potency of the remedy is, within certain limits, in the ratio of the atmospheric condensation.

To express this truth mathematically is not difficult. Thus, when a represents the amount of blood of the whole body, _b_ the amount of the remedy, _e_ the amount of atmospheric compression, and _x_ the pharmaco-dynamic potentiality which we are seeking, we shall then have the simple formula:

b x e
x = -----
a

A definite conception of the truth of this proposition will, I think, be more readily attained by the presentation of the steps which led me to its discovery.

Let me begin, then, by stating that my attention was attracted several years ago by that unique complex of symptoms known as the "caisson or tunnel disease." As most physicians are aware, the caisson disease is an affection of the spinal cord, due to a sudden transition from a relatively high atmospheric pressure to one much lower. Hence, those who work in caissons, or submerged tunnels, under an external pressure of two atmospheres or even more, are liable to be attacked by the disease shortly after leaving the tunnel. The seizure never, however, occurs while the subject is in the caisson, or in other words, while he remains under pressure. Moreover, when the transition from the condensed atmosphere to that of ordinary density is gradually accomplished, which may be done by letting the air escape from the lock very slowly, the caisson disease is rarely if ever set up. It is the systematic disregard of this principle by those who work in compressed air that is responsible, or largely responsible, for the occurrence of the disease.

The chief clinical features of the caisson disease are pain, which may be relatively mild, as when confined to a circumscribed area of one extremity, or of frightful intensity, as when it appears in the ears, knees, back, or abdomen; anaesthesia and paralysis, usually of paraplegic type; bladder symptoms, assuming the form of retention or incontinence; and, more rarely, rectal disturbances (usually incontinence).

These phenomena, or rather some of them, appear some time within half an hour after the subject has left the compressed atmosphere. It was while investigating this most interesting affection as it occurred in the course of the construction of the Hudson River tunnel, that I was able, at the same time, to study the effects of compressed air upon the organism, and especially upon the nervous system, as exhibited in a large number of persons.

The results of these studies I now submit without hesitation, and in all candor, to the judgment of the profession, believing, as I certainly do, that their practical significance from a neuro-therapeutic standpoint is assured. Without anticipating, however, let me state that the first thing which impressed me about compressed air was its extraordinary effect upon cerebral and cerebro-spinal function.