56 
SIR J. B. LA WES AND PROFESSOR J. H. GILBERT ON THE 
In the experiments of the first series, with a range of from 1'56 to 1‘96 gram of 
combined nitrogen supplied, there were, in several cases, indicated gains of 0‘5 gram, 
or more; and in one case the gain amounted to 0'865 gram. In the experiments of 
the second series, with a total supply in sand and manure generally ranging from 
0'3 to 0'5 gram, there was, in one case a loss, in five cases the gain was less than 
O'l gram, and in no instance did it reach 0'2 gram. M. Joulie attributes the less 
amount of gain in the second series, to the much shorter period of vegetation involved. 
Reviewing the results of the two series of experiments, M. Joulie says the 
variable quantities of nitrogen gained cannot be attributed to dust, ammonia, or other 
compounds of nitrogen, in the air, as all the pots were equally exposed to these; 
whilst there is a range from 0‘1075 gram loss, to 0‘8654 gram gain of nitrogen, the 
difference amounting to nearly 1 gram. The result must be due, therefore, to the 
fixation of the free nitrogen of the air, either in the soil or by the plant. M. Berthelot 
attributed the result in his experiments to the clay soil, under the influence of microbes ; 
but M. Joulie cannot go so far. It was, however, true that, in his experiments, the 
surface of the water in the pots and the surface of the soils showed myriads of 
microbes. He asks—if such bodies can cause the fixation of free nitrogen, why should 
not grouped cells, as in the case of the higher plants, have the same power? 
He further says—as plants have the power of causing the combination of carbon 
with the elements of water, after having decomposed carbonic acid, whilst chemists 
can only reduce it to carbonic oxide ; as MM. Thenaed have succeeded in bringing 
nitrogen into combination with the elements of water; and as M. Berthelot has 
shown that free nitrogen is brought into combination with dextrine and cellulose 
under the influence of the silent electric discharge—it is only a logical consequence 
that free nitrogen should be brought into combination within the plant. In* reference 
to this argument it may be oberved that the jiarallelism of the action by which free 
nitrogen combines with the elements of water in the laboratory, with that by which 
carbon and the elements of water combine within the plant, only holds good on the 
assumption that the carbon of the carbonic acid is first reduced to the free state, and 
so combines with the elements of water, without the intervention of its own oxygen. 
M. Joulie compares the amounts of nitrogen fixed in his various experiments with 
the amounts of crop produced, and observes that the gains have no relation to the 
amount of vegetation. He next comments on the connection between the condition 
of manuring of the various soils, and the amounts of nitrogen gained. Referring to 
the results of the first series of experiments, he points out that whilst without manure 
the gain was 0'491 gram, it was raised to 0’513 gram by purely mineral manure. 
Again, whilst the addition to the mineral manure of 0'3 gram nitrogen as nitrate of 
soda only gave a further gain of 0‘038 gram, and the addition of calcium carbonate 
increased the fixation by only 0‘0950 gram, the addition of caustic lime increased the 
fixation by 0'352 gram. It appeared, therefore, that lime exercised a very favourable 
influence on the phenomenon. 
