experimental pressure in the reaction chamber was measured. The apparatus
was firstly exhaustively tested for leaks. The Schaffer-manometer was capable
of measuring 0–60 kg cm
−2 excess pressure (i.e., up to *60 atm). Its scale
was divided on a circle of 24 cm diameter where each ‘stroke’ accurately
measured pressure differences as small as 0.05 kg cm
−2 (*0.05 atm). Even
with such accuracy, no detectable loss was observed over prolonged periods at
30 atm. To maintain precision, the manometer was re-calibrated between
every experimental determination.
The quantitative determinations so heavily criticised by Nernst in
Hamburg were confidently retained by the two men, ammonia now being
absorbed by 0.05 N hydrochloric acid and residual acid being titrated with
0.0523 N potassium hydroxide using methyl orange as indicator. Predictably,
as reflected by the higher concentrations of acid and alkali used, typical
ammonia yields at the higher pressure were now of the order of milligrams—
depending on the temperature and volume of gas—rather than the fractions
of a milligram obtained at atmospheric pressure. With yields now in the
region of 10–100 times larger, Nernst’s major criticism was finally laid to rest.
6.3 Then Secondly …
‘Bestimmung …’ probably introduced a prototype of what was to eventually
become an essential component of high pressure chemistry viz., a special
‘conical valve’—designed entirely by Robert—and with which he could
achieve precise control of gas flows through the apparatus.
18 By means of this
device, together with a ‘gas clock’ Robert was able to pass accurately measured
volumes of the pressurised gases through the reaction chamber for 30–
300 min depending on the volumes used and the temperatures of the
experiments. Once equilibrium was achieved the valve allowed the gas to be
moved effortlessly on through the absorption bottles. For the later form of
this invention he was to obtain a lower form of German patent or
‘Gebrauchsmuster’ and eventually an award equivalent to £500—‘a lot of
money at that time for an impecunious student!’ he was later to comment.
4
Indeed, it amounted to about ten years salary at the time.
Having established the integrity of their apparatus and now with precise
control of the gas flow, the two men conducted 56 pressurised experiments
reporting a series of 27 of these in temperature groups of ‘700 °C’, ‘800 °C’,
‘900 °C’, and ‘974 °C’. Here they examined the formation of ammonia using
stoichiometric mixtures of nitrogen and hydrogen obtained from the
decomposition of commercial ammonia, and mixtures produced after
6 Bestimmung Des Ammoniakgleichgewichtes Unter Druck
133
was firstly exhaustively tested for leaks. The Schaffer-manometer was capable
of measuring 0–60 kg cm
−2 excess pressure (i.e., up to *60 atm). Its scale
was divided on a circle of 24 cm diameter where each ‘stroke’ accurately
measured pressure differences as small as 0.05 kg cm
−2 (*0.05 atm). Even
with such accuracy, no detectable loss was observed over prolonged periods at
30 atm. To maintain precision, the manometer was re-calibrated between
every experimental determination.
The quantitative determinations so heavily criticised by Nernst in
Hamburg were confidently retained by the two men, ammonia now being
absorbed by 0.05 N hydrochloric acid and residual acid being titrated with
0.0523 N potassium hydroxide using methyl orange as indicator. Predictably,
as reflected by the higher concentrations of acid and alkali used, typical
ammonia yields at the higher pressure were now of the order of milligrams—
depending on the temperature and volume of gas—rather than the fractions
of a milligram obtained at atmospheric pressure. With yields now in the
region of 10–100 times larger, Nernst’s major criticism was finally laid to rest.
6.3 Then Secondly …
‘Bestimmung …’ probably introduced a prototype of what was to eventually
become an essential component of high pressure chemistry viz., a special
‘conical valve’—designed entirely by Robert—and with which he could
achieve precise control of gas flows through the apparatus.
18 By means of this
device, together with a ‘gas clock’ Robert was able to pass accurately measured
volumes of the pressurised gases through the reaction chamber for 30–
300 min depending on the volumes used and the temperatures of the
experiments. Once equilibrium was achieved the valve allowed the gas to be
moved effortlessly on through the absorption bottles. For the later form of
this invention he was to obtain a lower form of German patent or
‘Gebrauchsmuster’ and eventually an award equivalent to £500—‘a lot of
money at that time for an impecunious student!’ he was later to comment.
4
Indeed, it amounted to about ten years salary at the time.
Having established the integrity of their apparatus and now with precise
control of the gas flow, the two men conducted 56 pressurised experiments
reporting a series of 27 of these in temperature groups of ‘700 °C’, ‘800 °C’,
‘900 °C’, and ‘974 °C’. Here they examined the formation of ammonia using
stoichiometric mixtures of nitrogen and hydrogen obtained from the
decomposition of commercial ammonia, and mixtures produced after
6 Bestimmung Des Ammoniakgleichgewichtes Unter Druck
133