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The samples which are referred to under the numbers 1 to 7 were labelled as follows, viz.

1. Brockwell South Return. Driving road. First pillar from shaft.

2. Brockwell North Return. On outbye side hitch. Stenton double way. A few pillars in.

3. Busty Seam. Just round corner. Off bottom.

4. Do. do. Off side. (Note.– This sample was contained in an envelope placed within that holding the sample No. 3.)

5. Townley Seam. Close to shaft bottom. In intake. Off floor.

6. Townley Seam. Off sides. (Note.– This sample was contained in an envelope placed within that holding No. 5 sample.)

7. Dust from floor at curve off Busty shaft siding into West way.

All the samples were found to contain pieces of shale, coal, and wood larger than could be considered dust. To isolate the latter for exact comparison each sample was riddled through a gauze sieve having 25 meshes to the lineal inch, this being almost exactly the size of the gauze used for the Davy safety lamp. This fine dust was used for the determination of volatile matter, carbon, &c., and the proportion of such fine dust in the several samples is as follows, viz.

	No. 1.	No. 2.	No. 3.	No. 4.	No. 5.	No. 6.	No. 7.
	Per cent.	Per cent.	Per cent.	Per cent.	Per cent.	Per cent.	Per cent.
Proportion of fine dust, i.e., dust passing through sieve of 25 meshes to the lineal inch	43.3	38.4	45.3	57.7	47.6	76.0	55.4

It will be noted that five of the samples were taken from the floor, and two, viz., Nos. 4 and 6, from the sides of the drives or ways. The two samples, Nos. 4 and 6, had the largest proportions of real dust.

In case any point should arise as to the relative fineness of the portions of the sample which did not pass through the 25 mesh sieve these coarser portions were further sifted and the percentages retained by sieves of 5, 11, 20 and 25 meshes to the lineal inch noted. There were as follows, viz.

Percentage of Sample retained by Sieve of –	No. 1.	No. 2.	No. 3.	No. 4.	No. 5.	No. 6.	No. 7.
	Per cent.	Per cent.	Per cent.	Per cent.	Per cent.	Per cent.	Per cent.
5 meshes to the lineal inch	11.9	17.4	11.3	7.7	17.4	–	3.1
11 Do. do.	14.9	15.1	13.2	11.5	12.7	–	9.2
20 Do. do.	19.4	19.8	17.0	15.4	14.3	–	18.5
25 Do. do.	10.4	9.3	13.2	7.7	7.9	24.0	13.8

The examination of the fine dust yielded the following results, viz.

	No. 1.	No. 2.	No. 3.	No. 4.	No. 5.	No. 6.	No. 7.
	Per cent.	Per cent.	Per cent.	Per cent.	Per cent.	Per cent.	Per cent.
Moisture	1.6	1.5	1.6	1.6	1.4	1.4	1.3
Volatile combustible matter	18.4	20.2	25.0	22.8	22.0	21.3	22.9
Fixed carbon	44.5	47.6	45.6	48.6	47.3	54.5	54.7
Mineral substance (ash)	35.5	30.7	27.8	27.3	29.3	22.8	21.1
	100.0	100.0	100.0	100.0	100.0	100.0	100.0

It will be observed that Nos. 6 and 7 contain the smallest proportion of mineral matter and the largest proportions of fixed carbon. The percentage of volatile combustible matter is in one case as low as 18.4 and in another as high as 25.0 but in the remaining five samples only varies between 20.2 and 22.9. The largest proportion of mineral matter – 35.5 per cent. – is present in No. 1 sample, this being noticeably higher than in either of the other samples which range from 30.7 per cent. downwards.

All the samples coke on heating, practically the whole residue consisting in each case of a hard coke. In this respect the samples appear to be alike.

Microscopical examination failed to reveal the presence of fused particles in any case and in this respect again the samples do not differ.

E. GRANT HOOPER.

T. E. THORPE.

per H. W. W.

Government Laboratory.

26th March, 1909.