suitable, for all purposes to which the heat of gas is applied, the question naturally suggests itself: Why should we not discard the production of hydrocarbon gas, which is costly to produce, and adopt the cheaply produced water gas in preference ?

That question leads us to consider the question: What is the best quality of gas to supply, or, in other words, what are the factors that have to be taken into consideration in deciding the value of a gas to the user? This brings us to the link connecting the technical and the commercial aspects of the question.

What Price per Unit of Energy?

The main commercial factor is: What does it cost the con. sumer, or rather what price per unit of energy has he to pay, for his supply of gas; this supply being, upon the average of his wants, of the kind best suited for his purpose? The price must cover the cost of manufacture and distribution and the interest and other taxes upon the capital invested in the undertaking. The conditions which determine these main factors in the commercial problem are, from` a great variety of causes, subject to considerable differences, and, as a consequence, the price per unit of energy is necessarily variable. Further, as these conditions are subject to changes due to the advance of our technical knowledge of how to manufacture, distribute, and utilize the energy conveyed by the gas, there can be no one quality of gas which is, under all circumstances, the best to supply.

While that is the case, however, we may with advantage consider some of those technical-commercial conditions which have a dominating influence on the cost of energy to the gas consumer; and in considering these factors, the calorific power of the gas will be the only characteristic taken into account, as that is the one which can be more reliably determined by experiment, and which is rapidly becoming the most generally useful factor in respect of transmission of energy.

As already stated, the commercial consideration which mainly decides the quality of gas best suited to the consumer is that the quality should be such that it can be supplied through the consumers' meters at the least charge per unit of energy. Energy in the concrete form of coal is sold by weight of coal; and the price includes the cost of mining, the cost of storing, if necessary, and carriage to the point of consumption. Gas is sold by volume, and the price includes the cost of production, of storage, and of distribution; and just as coal costs sometimes more per ton for binging it until it is required and carrying it to the point of consumption than it does to mine it, so does gas sometimes cost more for its storage and distribution than it does for its

production. A coal with a comparatively low calorific value might possibly be so easily mined as to cost much less per ton than another coal with a comparatively high calorific value, and, in consequence, it might supply heat at a lower cost per unit at the mine or in the immediate vicinity than the better coal; but gradually, as the distance from the mine to the point of consumption increased, and as the cost for carriage also increased, the coal with the higher calorific value, although much more costly at the mine, might, with the added carriage, become the cheaper coal to the consumer, as it would supply the heat at a less cost per unit at the place of consumption.

To illustrate the point under consideration, we may, by way of example, compare the cost of water gas with a calorific value of 300,000 heat units per 1000 cubic feet, that of coal gas of 600,000, and that of cannel gas of 900,000 heat units. These three gases have, respectively, no illuminating power, and, approximately, 15 and 28 candle power. The cost of producing these three gases will vary according to the position of the works, upon which will depend the cost of gas-producing materials and the value of residuals; and, therefore, on making the comparison, it is necessary to arrive, as nearly as is possible, at the average costs, and then to compare the results which would be obtained under the altered relative costs of each gas, due to difference of conditions which affect the works producing and distributing it.

Different Results under Different Conditions.

I have assumed the average costs of production to be, water gas 4d., coal gas 12d., and cannel gas 24d. per 1000 cubic feet. I still further assume that the average capital and other on-cost fixed charges, irrespective of quality of gas, will be about 20d. per 1000 cubic feet; and these, added together, will be the cost per 1000 cubic feet to the consumer. The figures are embodied in the following table of costs:

It will be found, on consulting available statistics, that these assumed costs and values, as given in the table, are fairly near the averages that have obtained for many years past. As already stated, they are subject, from various causes, to great differences; but by changing the costs given in the columns of the table so as to suit the altered conditions, it will be easy to calculate what would be the best quality of gas to supply under those altered conditions.

As regards the higher quality of gas, there is no doubt that the figures given in the table apply to the greater part of Scotland, as gas with the higher calorific values represented has been supplied to the consumers in a number of towns at even correspondingly lower prices; and under such conditions, cannel or higher quality gas is the best to supply.

If the distance from the source of the supply, or if the cost of materials for the production of the higher grades of gas, were to increase, and if the cost of the lower grades of gas decreased, the conditions would change, and the balance of advantage might be otherwise; and, in the same way, the present extraordinary rise in the cost of materials generally might possibly change the relative values of the different grades of gas. But in the discussion which followed the reading of Mr. Livesey's paper (at the recent Institution meeting), advocating a reduction in the grade of gas in London, Mr. Herring made it plain that here, in Scotland, the recent change in prices had been in favour of the higher grades of gas.

I am quite aware that there are a number of other minor factors which should have been taken into consideration in estimating the relative values of the different grades of gas, and that these factors are both technical and commercial-such as the unit of on-cost per 1000 cubic feet required to pay capital and other charges, and the relative values of the unit of heat for different calorific purposes.

What is Our Duty?

There is also another side of the question as to what is the best grade of gas supply-namely, What grades of gas supply will yield the most profit to the manufacturer and the supplier of gas ? The consumer looks to the price per 1000 cubic feet. He does not consider its calorific value, any more than the user of a penny-in-the-slot meter considers the extra price he has to pay for the check thereby put upon his improvidence. As it is put by Mr. Livesey: "The public were asking for a cheaper gas; they knew nothing about a lower power." We can form our

own opinion as to the attitude we ought to take up in regard to this aspect of the matter. Besides, these and other points will be best brought out by the general discussion of the whole subject which I hope will follow the reading of this paper.

Gas Under High Pressure.

There is, however, one other point to which I might be allowed to draw your attention before concluding, in reference to the supply of the different grades of gas. That is, the supply of gas under high pressure, just as electricity is supplied under high pressure, and with a very similar object-lowering the cost of distribution or carriage to the point of consumption.

The calorific value per unit of volume of high-grade gas may be looked upon as being due to the power which the carbon possesses of combining with hydrogen and condensing much hydrogen into small volume. The equivalent of that chemical condensation, in enabling gas to be economically distributed or carried to long distances, is mechanical compression. The natural gas in the United States is locked up in the earth's crust under enormous pressure; and, when tapped, it can be economically conveyed for long distances. Its high calorific value and high pressure enable a pipe of small diameter to convey to a distance a large amount of heat energy through the medium of gas; and recently in the United States a similar system has been adopted for the transmission of coal gas to long distances-the gas being compressed mechanically at the point of production, and reducing governors being used at the point of distribution.

We have seen that water gas is far and away the cheapest gas per unit of heat energy at the point of production, but that, owing to its low calorific value per unit of volume, it becomes the most expensive to carry long distances. By using up a small part of the low-priced water gas at the point of production, it would be possible, by means of a gas-engine and compressing pumps, to confer upon the bulk of the remaining water gas a high pressure that would enable it to be more economically distributed in a variety of ways, which will at once suggest them. selves to your practical minds.

ELECTION OF OFFICE-BEARERS.

The PRESIDENT said the ballot had resulted in the following having been elected office-bearers for the coming year :— President.-Mr. W. R. Herring, of Edinburgh.

Vice-Presidents.-Mr. Jas. Henderson, of Newton-on-Ayr; and Mr. John Wilson, of the Tradeston Gas-Works, Glasgow.

Hon. Secretary and Treasurer.-Mr. R. S. Carlow, of Arbroath. Committee.-Mr. D. Vass, of Airdrie; Mr. D. Robertson, of Dunoon; Mr. W. Blair, of Helensburgh; and Mr. T. Carmichael, of Barrhead.

Auditor.-Mr. R. B. Main, of Glasgow.

NEXT PLACE OF MEETING.

The place of meeting next year will be Glasgow, because of the Exbibition which is to be held there.

VOTES OF THANKS, ETC.

The PRESIDENT said they had gone through one of the best programmes the Association had ever had; and he asked the members to accord a hearty vote of thanks to the gentlemen who had taken so much trouble in the preparation of papers.

This was agreed to.

Mr. H. POOLEY presented Mr. Ewing with the President's Medal for the year. He said he knew he only voiced the wishes of every member of the Association, when he expressed the hope that Mr. Ewing might be long spared to wear his medal.

The PRESIDENT thanked the Association with all sincerity for their kindness in presenting him with the medal.

Mr. A. MACPHERSON proposed a vote of thanks to the Secretary; and it was carried.

Mr. CARLOW, in returning thanks, said the position of the Association was improving every year.

This concluded the meeting.

In the evening, a large company of members and their friends -ladies and gentlemen-dined together in the Balmoral Hotel —Mr. Ewing presiding. A brief toast-list was gone through.

On Friday, a party of about 120 journeyed to Lanark, whence they drove to the far-famed Falls of Clyde, which were seen to the best advantage. On returning to Lanark, luncheon was served in the Clydesdale Hotel. Several hours were thereafter at the disposal of the excursion ists, in which to visit the objects of interest in the ancient Royal Burgh and its neighbourhood. Tea was partaken of about six o'clock; and this was the closing proceeding of a meeting in which there had been nothing but happiness and good feeling from beginning to end. The weather during the day was bright and pleasant.