On the occasion in question, Neal sent James Archer, a lodger who lived at his house, to collect daff for Hardaker's humbugs from druggist Charles Hodgson.
Hodgson's pharmacy was 3 miles (4.8 km) away at Baildon Bridge in Shipley.
Hodgson was at his pharmacy, but did not serve Archer owing to illness and so his requests were seen to by his young assistant, William Goddard.
Goddard asked Hodgson where the daff was, and was told that it was in a cask in a corner of the attic.
However, rather than daff, Goddard sold Archer 12 pounds (5.4 kg) of arsenic trioxide.

The mistake remained undetected even during manufacture of the sweets by James Appleton, an "experienced sweetmaker" employed by Neal, though Appleton did observe that the finished product looked different from the usual humbugs.
Appleton was suffering symptoms of illness during the sweet-making process and was ill for several days afterwards with vomiting and pain in his hands and arms, but did not realise it was caused by poison.
40 pounds (18 kg) of lozenges were sold to Hardaker who also noticed the sweets looked unusual and used this to obtain a discount from Neal.
Like Appleton, Hardaker, as one of the first to taste the sweets, also promptly became ill.

Regardless, Hardaker sold 5 pounds (2.3 kg) of the sweets from his market stall that night – reportedly at a price of 1½d for 2 ounces (57 g).
Of those who purchased and ate the sweets, 21 people died with a further 200 or so becoming severely ill with arsenic poisoning within a day or so.
On the occasion in question, Neal sent James Archer, a lodger who lived at his house, to collect daff for Hardaker's humbugs from druggist Charles Hodgson. Hodgson's pharmacy was 3 miles (4.8 km) away at Baildon Bridge in Shipley. Hodgson was at his pharmacy, but did not serve Archer owing to illness and so his requests were seen to by his young assistant, William Goddard. Goddard asked Hodgson where the daff was, and was told that it was in a cask in a corner of the attic. However, rather than daff, Goddard sold Archer 12 pounds (5.4 kg) of arsenic trioxide.
The mistake remained undetected even during manufacture of the sweets by James Appleton, an "experienced sweetmaker" employed by Neal, though Appleton did observe that the finished product looked different from the usual humbugs. Appleton was suffering symptoms of illness during the sweet-making process and was ill for several days afterwards with vomiting and pain in his hands and arms, but did not realise it was caused by poison. 40 pounds (18 kg) of lozenges were sold to Hardaker who also noticed the sweets looked unusual and used this to obtain a discount from Neal. Like Appleton, Hardaker, as one of the first to taste the sweets, also promptly became ill.
Regardless, Hardaker sold 5 pounds (2.3 kg) of the sweets from his market stall that night – reportedly at a price of 1½d for 2 ounces (57 g). Of those who purchased and ate the sweets, 21 people died with a further 200 or so becoming severely ill with arsenic poisoning within a day or so.
1858 Bradford sweets poisoning