216 
rOPULAE SCIENCE REVIEW. 
the form of a crystalloid phosphate. The nutrition of the abnormal gi’owtb 
accounts for the absence of any smell of decomposition, which is nearly in- 
variably observed at the post-mortem examination when performed shortly 
after death from consumption, (e) The process of softening of the tuber- 
cular substance appears due to a loss of colloid power ; it can hardly be 
owing to an increase in the proportion of water, as there is but very little 
more water in softening tubercular lungs than in healthy lungs. 
How to Distinguish Cancer from Innocent Growths. — Dr. I. N. Dun- 
forth, in writing on the subject of the great difficulty of recognising can- 
cerous growths under the microscope, says that in conclusion he would lay 
down the following simple rules for drawing the distinction between 
innocent and morbid growths : whenever a description of one of the cells of 
a microscopic specimen is a description of all of its cells, the chances are as 
ten to one that it is not cancer ; whenever, on the other hand, the cells of 
such a specimen are so varied in form and size that philology, and ingenuity, 
and imagination, and the most unflinching resolution combined, utterly fail 
to accomplish the task of describing them, the chances are as ten to one 
that the specimen is from a malignant growth, whatever may be its name or 
location. 
METALLUKGY, MINERALOGY, AND MINING. 
The Manufacture of Iron. — A lecture, especially interesting to iron and 
steel manufacturers, was delivered on Thursday evening, March 20, to a 
crowded audience of the Fellows of the Chemical Society, at Burlington 
House, by Dr. C. William Siemens, F.R.S., on the manufacture of wrought 
iron and cast steel direct from iron ore by a new method, which is in- 
tended to supersede most of the present operations. By this process the 
blast furnaces, as well as the laborious puddling operations, are suppressed ; 
the ore being simply deoxidised, and the iron precipitated in a new furnace,^ 
specially arranged for the purpose, from which it is withdrawn in the state 
of blooms, and at once shingled or melted into steel. The special feature, 
however, and the one of the greatest interest at the present time, is the 
extraordinary economy of fuel effected by this invention. In place of some 
four tons of the best coal, as by existing processes is required to obtain a ton 
of wrought iron, but 28 cwt. of coal of an inferior coal is necessary to pro- 
duce the same weight. 
Changes in Coal owing to Exposure. — A valuable paper on this subject, but 
one too long for abstract, is that by Mr. H. Engelmann in the “ Chemical News” 
[Jan. 10, 1873]. The author gives actual experiments showing the extreme 
loss which coal undergoes by storage. He says that an interesting experi- 
ment was made some years ago in Germany to test the deterioration by ex- 
posure of Silesian gas coal. A quantity of coal slack was divided in three 
parts. One part was directly used in the gas factory, another after having 
been housed one month, and the third after one month’s exposure in the 
yard. The relative proportions of gas obtained were 135, 111, 95, The 
losses by exposure were therefore 17-2 per cent, and 29’5 per cent. The 
gas coke from the first lot was serviceable, from the second and third un- 
serviceable. The rest of this paper is full of interest. 
