An Algerian man has been convicted of plotting to spread ricin and other poisons. The BBC News website looks at some of the substances which he planned to use in Britain.
Ricin was described by a chemical weapons expert from Porton Down as one of the most toxic plant poisons known to man.
The main ingredient is castor oil beans and 22 of these were found in a flat in Wood Green, north London. But although an initial test for ricin proved positive, a later test proved inconclusive.
Several recipes were found in this flat in Wood Green
The original recipe for ricin was on a single piece of paper found in a locked bag at the flat in Wood Green. It was written, in Arabic, by Bourgass on both sides of a piece of paper measuring six inches by five inches. The word ricin could be seen and there were electrical circuits drawn on the back.
Two other series of recipes, one written by Bourgass and the other photocopied, were also found in Wood Green.
A fourth set, the result of photocopying the originals, was found hidden at the bottom of a holdall in David Khalef's rented house in Thetford, Norfolk.
Khalef was later cleared of involvement in the conspiracy by a jury at the Old Bailey.
The trial heard details about how ricin is created, using crushed castor oil beans.
The powdery residue is tasteless and odourless, deteriorates in cooking and does not show up in a post-mortem examination.
The court heard that it requires only between five and 10 millionths of a gram per kilogram of body weight to kill, so one gram would be fatal within a few days.
Apple seeds and ground cherry stones were found, both of which can be used to make cyanide.
The recipes suggested three different ways of making cyanide.
Cherry stones can be used to make cyanide
It is nowhere near as toxic as ricin (30,000 apple seeds would be needed to produce a lethal dose) but can be delivered through food or gas.
One of the recipes recommended using apricot seeds.
The third recipe would require a gas mask during production.
Rotten meat poison (Botulinum)
Botulinum is the most toxic substance known to man and can be used to create outbreaks of botulism.
One gram from this recipe could kill 80,000 people within six days.
It can be used in food or drink for up to 12 days or sprayed using a fly spray. But the recipe was likely to be ineffective because bacteria would outgrow the botulinum, making it relatively harmless.
The tubers of potatoes can be used to make solanine, which is 1,000 times less toxic than ricin.
The poison solanine can be produced from potatoes
Two kilos of potatoes would produce 130 milligrams of solanine - a fatal dose is 200 to 400 milligrams if eaten.
Traces of this were said to have been found in a sealed Nivea jar.
It would be delivered into the body in one dose of 80 milligrams which, because it cannot be metabolised, causes coma and death.
A bottle of isopropanol - key to the production of nicotine poison - was also found at the flat.
Police found a bottle of acetone, which they claimed could have been used to extract poisons.
They also discovered a pestle and mortar used for grinding, a funnel, several packets of blotting paper, rubber gloves, a coffee grinding mill and a set of scales.