Early the next morning, Guo Song came to Laojunguan, the simple warehouse behind has been built, a large amount of saltpeter and sulfur are placed, there is another building in front of the warehouse, here is the saltpeter purification workshop, fifty soldiers and fifty skilled craftsmen here to purify nitrate.

Nitrate powder purification and purification is actually relatively simple, that is, the crystallization method, after dissolving saltpeter powder with water at seventy or eighty degrees, and then filtering the insoluble impurities, the crystals filtered out after cooling are relatively pure nitrate powder, and then repeated many times to get enough pure nitrate powder.

The sulfonite method is mainly to identify whether the crystals obtained are miscanthus nitrate, or fire nitrate, miscanthus nitrate mixed with sulfur ignition is not combustible, and fire nitrate will burn violently, in fact, it has little significance to Guo Song.

There are three processes, the first process is to mash the saltpeter, grind it into powder with a small stone, the second process is to dissolve and purify, and the third process is the sulfonite sampling test.

The head of this workshop is a school captain, called Ren Ning, who also followed Guo Song to Anxi back then, he is a little older, he is nearly forty years old, and it is not suitable for the battlefield, he is mainly responsible for logistics, Guo Song needs a completely trustworthy general to take charge of this matter, and Ren Ning was chosen.

Ren Ning is cautious, conscientious and responsible, and is indeed the most suitable candidate.

He took Guo Song to visit the completion workshop, and then led Guo Song to the small warehouse behind.

"It's all pure fire powder, and according to the envoy's order, the fire source is absolutely not allowed here."

Ren Ning took out the key to open the big iron lock, pushed open the door, and Guo Song saw rows of wooden shelves, on which were placed clay pots filled with white nitrate.

Guo Song opened a lid and reached out to grab a handful of nitrate, which leaked out from between his fingers like fine salt.

"How many are there?" Guo Song asked.

"At present, there are a total of five hundred catties, fifty cans, and each can contains ten catties."

"What about the sulfur powder? Before, we had you grind it into powder as well. ”

"Yes! In another warehouse, that one does not need to be purified, in another small warehouse, we grind more than three thousand catties, and charcoal powder, we use the best charcoal to grind into powder, and there are also seven or eight hundred catties, and put it together with sulfur. ”

Guo Song nodded, turned back to a few soldiers and said: "Nitrate, sulfur and toner, take one can of each sample and send it to my big tent, and find a more accurate scale for me." ”

The soldiers began to pick up the goods, and Guo Song said to Ren Ning: "I will hand over another process to you, and the finished nitrate, toner and sulfur powder will be divided into packs, wrapped in paper, or packed in containers, one hundred taels of nitrate powder, five taels of toner and sulfur powder, and the weighing must be very accurate." ”

"The lowly duty must be done!"

..........

Back to the big tent, Guo Song and a few personal soldiers together, began to weigh, he once saw the production of firecrackers, remember very clearly, the formula of gunpowder is nitrate powder into five, sulfur powder into five, charcoal into five, plus a little sucrose, sucrose is a gas generator, can make the explosion more violent, at present can buy sucrose in Bashu, but it is more expensive, Chang'an can also buy.

Guo Song quickly prepared the first package of black powder in history in the unit of two, of course, Sun Simiao had already prepared it, and the nitrate powder and sulfur powder he used were one to one, and the combustion was very strong, but the explosion was not good.

But this kind of gunpowder like flour is not what Guo Song wants, it must be made into particles the size of mung beans so that it can be fully burned.

Generally, it is mixed into a paste with water, and then dried, but there is a very good way, not with water, with egg white to reconcile and condense, of course, a bit of luxury, there is castor oil, adding castor oil is nitroglycerin, soil explosives, the explosive force is more violent, castor seems to be introduced from Tianzhu in the Tang Dynasty, but the market does not seem to have seen it, Guo Song has asked Zhang Lei to look for this kind of castor.

After Guo Song stirred with egg whites, the gunpowder had already adhered to a ball, and the underside needed to be dried and then coarsely ground.

He handed over this matter to his own soldiers, and he had to rush back to the official office of Jiedu Mansion, and there was urgent news from Longyou.......

The news came from a Sogdian who was doing business in Longyou by pigeon letter, that 20,000 Tibetan troops had entered the Hehuang Valley, and that a large number of people had fled, and that the defenders of Shanzhou were only 2,000 people, and that 2,000 soldiers were evacuating in the direction of Lanzhou together with the people who had fled all over the city.

The civil officials and military generals in the hall were all together, very quiet, after listening to the report, Guo Song slammed his fist on the table, what he was most worried about still happened, Zhu Jun did not increase troops to the Hehuang Valley at all, and after the Hehuang soldiers and horses made Dai Lan was killed by the generals Zhang Tingzhi and Duan Cheng, the two led an army of 20,000 to the capital, the Hehuang Valley was completely empty, of course Tubo would not let go of such a good opportunity, what Tang Fan Alliance, everything became a joke.

Countless pairs of eyes looked at Guo Song, and Guo Song said slowly: "When I came back yesterday, Liang Wu told me that Tubo increased its troops to the Great Dou Tu Valley, adding four or five thousand people, and it is estimated that we are afraid that we will kill out of the Great Dou Tu Valley, but in any case, we can't sit idly by, we still have to recapture the southern section of the Great Dou Tu Valley and attack the Tubo army from behind." ”

At present, there are 32,000 people in Hexi, in addition to the 20,000 Ganzhou army, there are also 6,000 Shazhou militia army, as well as the 6,000 army brought back by Guo Song from Longyou and Dazhenguan, and then there is the 4,000 logistics army, which is mainly responsible for Tuntian.

At this time, Changshi Pan Liao said: "When the envoy was not there, several Qiang tribes said that once Hexi was in danger, they were willing to send troops to join the Tang army to fight, and they would probably be able to send 5,000 cavalry. ”

Guo Song nodded, "The matter of the Qiang people sending troops, we will discuss it later, now I want to know the situation of money and food and other armaments?" ”

Cui Wenjing has fled back to Chang'an, allegiance to Zhu Zhu, was appointed as a waiter of the Ministry of Rites, and he mixed well, Pan Liao reappeared, and the current governor of Hexi Jiedu and Ganzhou Governor Shi.

Pan Liao hurriedly said: "The grain situation is not bad, the stock of grain is 200,000 stones, 400,000 quintals of hay, after the wheat harvest this year, the stock of grain can reach 500,000 stones, there are 1.2 million sheep, and the money is 320,000 yuan, and the money brought back by the envoy this time has not been counted and put into storage, and there are 20,000 sets of unused armor in other materials, 5,000 pairs of bows and arrows and crossbow arrows, 150,000 war knives, 300,000 spears, 30,000 shields, 2,000 barrels of kerosene, 10,000 large tents, 80,000 war horses, and 5,000 camels. The 20,000 mules and donkeys brought back this time have not yet been disposed of, mainly these materials. ”

A man next to him got up and added: "To add to the humble position, there are 160,000 catties of pig iron, 80,000 catties of copper, 450 siege ladders, 20 cloud ladders, 40 trebuchets, and 2 large siege rams." ”

In fact, there was saltpeter and brimstone, which they had missed.

Guo Song took a few steps and said to Zhonglang General An Rengui: "There is a Longyou Weapons Manufacturing Institute under the Ordnance Supervision in Lanzhou, with more than 600 skilled craftsmen, you bring 2,000 cavalry and 3,000 mules and donkeys over, and bring these craftsmen and their families to Zhangye." ”

An Rengui bowed down and said, "Obey the order!" ”

Zhang Qiu'an, who joined the army, reminded: "Bring another 2,000 camels, there are a lot of armor and materials in stock, and they will be transported back together!"

A sentence reminded Guo Song, he thought about it and said: "A large number of people on the right side of Longyou have fled, mainly to Guanzhong, and some will flee to Hexi, the number will not be small, we must be ready to receive it, Pan Changshi, you guys will come up with a plan!" ”

"Obey the order!"

The situation in Longyou was critical, and the entire military and political government began to operate.

Guo Song rushed back to the barracks and began to deploy the attack on Dadou Bagu.

He ordered Zhonglang to lead Li Bing with 5,000 men to increase his troops to Dadou Bagu, and Kangbao's Modao military camp and Zhonglang General Yang Miao's heavy crossbow battalion also rushed to Dadou Bagu.

At present, there are 3,000 troops stationed in Dadou Bagu, and Luo Daxiao is in charge of Zhonglang.

Guo Song ordered Liang Wu to lead 5,000 troops to Liangzhou to garrison, Liangzhou was not threatened by the army before, but now it is difficult to say, once the Tubo people occupy Lanzhou, it is likely that they will go north to attack Liangzhou.

Guo Song wrote another letter, which was sent to Shuofang Jiedu Mansion and handed over to Cui Kuan, the envoy of Jiedu, who was very worried that the party members would be ready to move because of the Tubo army's attack on Longyou, and Cui Kuan wanted to guard against not Tubo, but the party people.

While deploying troops and sending generals, he did not forget the importance of intelligence, in fact, when he returned from Guanzhong, he sent the scout commander Zhang Yun and a hundred of his subordinates to Longyou to inquire about intelligence.

At noon the next day, the soldiers found him, and the gunpowder particles he asked for had been completed.